RESUMEN
The transcription of Arabidopsis organellar genes is performed by three nuclear-encoded RNA polymerases: RPOTm, RPOTmp, and RPOTp. The RPOTmp protein possesses ambiguous transit peptides, allowing participation in gene expression control in both mitochondria and chloroplasts, although its function in plastids is still under discussion. Here, we show that the overexpression of RPOTmp in Arabidopsis, targeted either to mitochondria or chloroplasts, disturbs the dormant seed state, and it causes the following effects: earlier germination, decreased ABA sensitivity, faster seedling growth, and earlier flowering. The germination of RPOTmp overexpressors is less sensitive to NaCl, while rpotmp knockout is highly vulnerable to salt stress. We found that mitochondrial dysfunction in the rpotmp mutant induces an unknown retrograde response pathway that bypasses AOX and ANAC017. Here, we show that RPOTmp transcribes the accD, clpP, and rpoB genes in plastids and up to 22 genes in mitochondria.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Cloroplastos , Regulación de la Expresión Génica de las Plantas , Germinación , Mitocondrias , Transcriptoma , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Mitocondrias/metabolismo , Mitocondrias/genética , Cloroplastos/metabolismo , Cloroplastos/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Germinación/genética , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , Plantones/genética , Plantones/crecimiento & desarrollo , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/genéticaRESUMEN
Bacteria often evolve antibiotic resistance through mutagenesis. However, the processes causing the mutagenesis have not been fully resolved. Here, we find that a broad range of ribosome-targeting antibiotics cause mutations through an underexplored pathway. Focusing on the clinically important aminoglycoside gentamicin, we find that the translation inhibitor causes genome-wide premature stalling of RNA polymerase (RNAP) in a loci-dependent manner. Further analysis shows that the stalling is caused by the disruption of transcription-translation coupling. Anti-intuitively, the stalled RNAPs subsequently induce lesions to the DNA via transcription-coupled repair. While most of the bacteria are killed by genotoxicity, a small subpopulation acquires mutations via SOS-induced mutagenesis. Given that these processes are triggered shortly after antibiotic addition, resistance rapidly emerges in the population. Our work reveals a mechanism of action of ribosomal antibiotics, illustrates the importance of dissecting the complex interplay between multiple molecular processes in understanding antibiotic efficacy, and suggests new strategies for countering the development of resistance.
Asunto(s)
Antibacterianos , ARN Polimerasas Dirigidas por ADN , Farmacorresistencia Bacteriana , Inestabilidad Genómica , Gentamicinas , Ribosomas , Antibacterianos/farmacología , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , Ribosomas/metabolismo , Ribosomas/efectos de los fármacos , Gentamicinas/farmacología , Farmacorresistencia Bacteriana/genética , Escherichia coli/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Mutación , Mutagénesis , Transcripción Genética/efectos de los fármacos , Biosíntesis de Proteínas/efectos de los fármacosRESUMEN
The emergence of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) has imposed further challenges to the clinical management of MRSA infections. When exposed to ß-lactam antibiotics, these strains can easily acquire reduced ß-lactam susceptibility through chromosomal mutations, including those in RNA polymerase (RNAP) genes such as rpoBC, which may then lead to treatment failure. Despite the increasing prevalence of such strains and the apparent challenges they pose for diagnosis and treatment, there is limited information available on the actual mechanisms underlying such chromosomal mutation-related transitions to reduced ß-lactam susceptibility, as it does not directly associate with the expression of mecA. This study investigated the cellular physiology and metabolism of six missense mutants with reduced oxacillin susceptibility, each carrying respective mutations on RpoBH929P, RpoBQ645H, RpoCG950R, RpoCG498D, RpiAA64E, and FruBA211E, using capillary electrophoresis-mass spectrometry-based metabolomics analysis. Our results showed that rpoBC mutations caused RNAP transcription dysfunction, leading to an intracellular accumulation of ribonucleotides. These mutations also led to the accumulation of UDP-Glc/Gal and UDP-GlcNAc, which are precursors of UTP-associated peptidoglycan and wall teichoic acid. Excessive amounts of building blocks then contributed to the cell wall thickening of mutant strains, as observed in transmission electron microscopy, and ultimately resulted in decreased susceptibility to ß-lactam in OS-MRSA. IMPORTANCE: The emergence of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) strains has created new challenges for treating MRSA infections. These strains can become resistant to ß-lactam antibiotics through chromosomal mutations, including those in the RNA polymerase (RNAP) genes such as rpoBC, leading to treatment failure. This study investigated the mechanisms underlying reduced ß-lactam susceptibility in four rpoBC mutants of OS-MRSA. The results showed that rpoBC mutations caused RNAP transcription dysfunction, leading to an intracellular accumulation of ribonucleotides and precursors of peptidoglycan as well as wall teichoic acid. This, in turn, caused thickening of the cell wall and ultimately resulted in decreased susceptibility to ß-lactam in OS-MRSA. These findings provide insights into the mechanisms of antibiotic resistance in OS-MRSA and highlight the importance of continued research in developing effective treatments to combat antibiotic resistance.
Asunto(s)
Antibacterianos , ARN Polimerasas Dirigidas por ADN , Staphylococcus aureus Resistente a Meticilina , Pruebas de Sensibilidad Microbiana , Oxacilina , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/enzimología , Oxacilina/farmacología , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , Antibacterianos/farmacología , beta-Lactamas/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Mutación Missense , Pared Celular/efectos de los fármacos , Pared Celular/metabolismo , Pared Celular/genética , Humanos , Mutación , MetabolómicaRESUMEN
RNA polymerases (RNAPs) carry out the first step in the central dogma of molecular biology by transcribing DNA into RNA. Despite their importance, much about how RNAPs work remains unclear, in part because the small (3.4 Angstrom) and fast (~40 ms/nt) steps during transcription were difficult to resolve. Here, we used high-resolution nanopore tweezers to observe the motion of single Escherichia coli RNAP molecules as it transcribes DNA ~1,000 times improved temporal resolution, resolving single-nucleotide and fractional-nucleotide steps of individual RNAPs at saturating nucleoside triphosphate concentrations. We analyzed RNAP during processive transcription elongation and sequence-dependent pausing at the yrbL elemental pause sequence. Each time RNAP encounters the yrbL elemental pause sequence, it rapidly interconverts between five translocational states, residing predominantly in a half-translocated state. The kinetics and force-dependence of this half-translocated state indicate it is a functional intermediate between pre- and post-translocated states. Using structural and kinetics data, we show that, in the half-translocated and post-translocated states, sequence-specific protein-DNA interaction occurs between RNAP and a guanine base at the downstream end of the transcription bubble (core recognition element). Kinetic data show that this interaction stabilizes the half-translocated and post-translocated states relative to the pre-translocated state. We develop a kinetic model for RNAP at the yrbL pause and discuss this in the context of key structural features.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Escherichia coli , Nanoporos , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/química , ARN Polimerasas Dirigidas por ADN/genética , Escherichia coli/metabolismo , Escherichia coli/genética , Transcripción Genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/química , Pinzas Ópticas , Cinética , Nucleótidos/metabolismoRESUMEN
Bacterial chromosomal DNA is structured and compacted by proteins known as bacterial chromatin proteins (i.e., nucleoid-associated proteins or NAPs). DNA-dependent RNA polymerase (RNAP) must frequently interact with bacterial chromatin proteins because they often bind DNA genome-wide. In some cases, RNAP must overcome barriers bacterial chromatin proteins impose on transcription. One key bacterial chromatin protein in Escherichia coli that influences transcription is the histone-like nucleoid structuring protein, H-NS. H-NS binds to DNA and forms nucleoprotein filaments. To investigate the effect of H-NS filaments on RNAP elongation, we developed an in vitro transcription assay to monitor RNAP progression on a DNA template bound by H-NS. In this method, initiation and elongation by RNAP are uncoupled by first initiating transcription in the presence of only three ribonucleoside triphosphates (rNTPs) to halt elongation just downstream of the promoter. Before elongation is restarted by addition of the fourth NTP, an H-NS filament is formed on the DNA so that transcript elongation occurs on an H-NS nucleoprotein filament template. Here, we provide detailed protocols for performing in vitro transcription through H-NS filaments, analysis of the transcription products, and visualization of H-NS filament formation on DNA by electrophoretic mobility shift assay (EMSA). These methods enable insight into how H-NS affects RNAP transcript elongation and provide a starting point to determine effects of other bacterial chromatin proteins on RNAP elongation.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Proteínas de Escherichia coli , Escherichia coli , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Transcripción Genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Elongación de la Transcripción Genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Proteínas Fimbrias/metabolismo , Proteínas Fimbrias/genéticaRESUMEN
All mRNA products are currently manufactured in in vitro transcription (IVT) reactions that utilize single-subunit RNA polymerase (RNAP) biocatalysts. Although it is known that discrete polymerases exhibit highly variable bioproduction phenotypes, including different relative processivity rates and impurity generation profiles, only a handful of enzymes are generally available for mRNA biosynthesis. This limited RNAP toolbox restricts strategies to design and troubleshoot new mRNA manufacturing processes, which is particularly undesirable given the continuing diversification of mRNA product lines toward larger and more complex molecules. Herein, we describe development of a high-throughput RNAP screening platform, comprising complementary in silico and in vitro testing modules, that enables functional characterization of large enzyme libraries. Utilizing this system, we identified eight novel sequence-diverse RNAPs, with associated active cognate promoters, and subsequently validated their performance as recombinant enzymes in IVT-based mRNA production processes. By increasing the number of available characterized functional RNAPs by more than 130% and providing a platform to rapidly identify further potentially useful enzymes, this work significantly expands the RNAP biocatalyst solution space for mRNA manufacture, thereby enhancing the capability for application-specific and molecule-specific optimization of both product yield and quality.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , ARN Mensajero , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/química , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transcripción Genética , Biocatálisis , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/químicaRESUMEN
Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is the first-line method for the rapid identification of most cultured microorganisms. As for Streptomyces strains, MALDI-TOF MS identification is complicated by the characteristic incrustation of colonies in agar and the strong cell wall of Actinomycetes cells requiring the use of alternative protein extraction protocols. In this study, we developed a specific protocol to overcome these difficulties for the MALDI-TOF MS identification of Actinomycetes made on solid medium. This protocol includes incubation of colony removed from agar plate with the beta-agarase enzyme, followed by a mechanical lysis and two washes by phosphate buffer and ethanol. Twenty-four Streptomyces and two Lentzea strains isolated from Algerian desertic soils were first identified by 16S rRNA sequencing as gold standard method, rpoB gene was used as a secondary gene target when 16S rRNA did not allow species identification. In parallel the isolates were identified by using the MALDI-TOF MS protocol as reported. After the expansion of the database with the inclusion of this MSPS, the strains were analyzed again in MALDI Biotyper, and all were identified. This work demonstrates that the rapid identification of Actinomycetes can be obtained without protein extraction step frequently used in MALDI-TOF mass spectrometry with this type of microorganisms.
Asunto(s)
Actinobacteria , ARN Ribosómico 16S , Microbiología del Suelo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , ARN Ribosómico 16S/genética , Argelia , Actinobacteria/aislamiento & purificación , Actinobacteria/genética , Actinobacteria/clasificación , Actinobacteria/química , ADN Bacteriano/genética , Streptomyces/aislamiento & purificación , Streptomyces/genética , Streptomyces/clasificación , Streptomyces/química , Proteínas Bacterianas/genética , ARN Polimerasas Dirigidas por ADN/genética , Medios de Cultivo/química , Análisis de Secuencia de ADN , Técnicas Bacteriológicas/métodos , Glicósido HidrolasasRESUMEN
Transcription has a mechanical component, as the translocation of the transcription machinery or RNA polymerase (RNAP) on DNA or chromatin is dynamically coupled to the chromatin torsion. This posits chromatin mechanics as a possible regulator of eukaryotic transcription, however, the modes and mechanisms of this regulation are elusive. Here, we first take a statistical mechanics approach to model the torsional response of topology-constrained chromatin. Our model recapitulates the experimentally observed weaker torsional stiffness of chromatin compared to bare DNA and proposes structural transitions of nucleosomes into chirally distinct states as the driver of the contrasting torsional mechanics. Coupling chromatin mechanics with RNAP translocation in stochastic simulations, we reveal a complex interplay of DNA supercoiling and nucleosome dynamics in governing RNAP velocity. Nucleosomes play a dual role in controlling the transcription dynamics. The steric barrier aspect of nucleosomes in the gene body counteracts transcription via hindering RNAP motion, whereas the chiral transitions facilitate RNAP motion via driving a low restoring torque upon twisting the DNA. While nucleosomes with low dissociation rates are typically transcriptionally repressive, highly dynamic nucleosomes offer less of a steric barrier and enhance the transcription elongation dynamics of weakly transcribed genes via buffering DNA twist. We use the model to predict transcription-dependent levels of DNA supercoiling in segments of the budding yeast genome that are in accord with available experimental data. The model unveils a paradigm of DNA supercoiling-mediated interaction between genes and makes testable predictions that will guide experimental design.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Nucleosomas , Transcripción Genética , Nucleosomas/metabolismo , Nucleosomas/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , ADN/metabolismo , ADN/química , ADN/genética , Cromatina/metabolismo , Cromatina/genética , ADN Superhelicoidal/metabolismo , ADN Superhelicoidal/química , ADN Superhelicoidal/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismoRESUMEN
Numerous molecular machines are required to drive the central dogma of molecular biology. However, the means by which these numerous proteins emerged in the early evolutionary stage of life remains enigmatic. Many of them possess small ß-barrel folds with different topologies, represented by double-psi ß-barrels (DPBBs) conserved in DNA and RNA polymerases, and similar but topologically distinct six-stranded ß-barrel RIFT or five-stranded ß-barrel folds such as OB and SH3 in ribosomal proteins. Here, we discover that the previously reconstructed ancient DPBB sequence could also adopt a ß-barrel fold named Double-Zeta ß-barrel (DZBB), as a metamorphic protein. The DZBB fold is not found in any modern protein, although its structure shares similarities with RIFT and OB. Indeed, DZBB could be transformed into them through simple engineering experiments. Furthermore, the OB designs could be further converted into SH3 by circular-permutation as previously predicted. These results indicate that these ß-barrels diversified quickly from a common ancestor at the beginning of the central dogma evolution.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Evolución Molecular , Modelos Moleculares , Proteínas Ribosómicas , Proteínas Ribosómicas/metabolismo , Proteínas Ribosómicas/química , Proteínas Ribosómicas/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/química , Pliegue de Proteína , Secuencia de AminoácidosRESUMEN
This report documents the case of a Ukrainian patient infected with an extensively drug-resistant (XDR) lineage 2 Mycobacterium tuberculosis strain harbouring the rifampicin resistance mutation RpoB I491F. This mutation is not detected by routine molecular WHO-recommended rapid diagnostics, complicating the detection and treatment of these strains. The occurrence of such mutations underscores the need for enhanced diagnostic techniques and tailored treatment regimens, especially in eastern Europe where lineage 2 strains and XDR-tuberculosis are prevalent.
Asunto(s)
Antituberculosos , Proteínas Bacterianas , ARN Polimerasas Dirigidas por ADN , Tuberculosis Extensivamente Resistente a Drogas , Mutación , Mycobacterium tuberculosis , Rifampin , Adulto , Humanos , Antituberculosos/uso terapéutico , Proteínas Bacterianas/genética , ARN Polimerasas Dirigidas por ADN/genética , Tuberculosis Extensivamente Resistente a Drogas/diagnóstico , Tuberculosis Extensivamente Resistente a Drogas/tratamiento farmacológico , Tuberculosis Extensivamente Resistente a Drogas/microbiología , Alemania , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/aislamiento & purificación , Mycobacterium tuberculosis/efectos de los fármacos , Rifampin/uso terapéutico , Ucrania , FemeninoRESUMEN
The remarkable success of messenger RNA (mRNA)-based vaccines has underscored their potential as a novel biotechnology platform for vaccine development and therapeutic protein delivery. However, the single-subunit RNA polymerase from bacteriophage T7 widely used for in vitro transcription is well known to generate double-stranded RNA (dsRNA) by-products that strongly stimulate the mammalian innate immune response. The dsRNA was reported to be originated from self-templated RNA extension or promoter-independent transcription. Here, we identified that the primary source of the full-length dsRNA during in vitro transcription is the DNA-terminus-initiated transcription by T7 RNA polymerase. Guanosines or cytosines at the end of DNA templates enhance the DNA-terminus-initiated transcription. Moreover, we found that aromatic residues located at position 47 in the C-helix lead to a significant reduction in the production of full-length dsRNA. As a result, the mRNA synthesized using the T7 RNA polymerase G47W mutant exhibits higher expression efficiency and lower immunogenicity compared to the mRNA produced using the wild-type T7 RNA polymerase.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Transcripción Genética , Proteínas Virales , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/química , Proteínas Virales/metabolismo , Proteínas Virales/genética , Proteínas Virales/química , Mutación , ARN Bicatenario/genética , ARN Bicatenario/metabolismo , Animales , ADN/metabolismo , ADN/genética , ADN/química , ARN Mensajero/genética , ARN Mensajero/metabolismo , Bacteriófago T7/genética , Bacteriófago T7/enzimología , RatonesRESUMEN
The genus Orthonairovirus includes highly pathogenic tick-borne viruses such as the Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV). A reverse genetics system is an indispensable tool for determining the viral factors related to pathogenicity. Tofla orthonairovirus (TFLV) is a recently identified virus isolated from ticks in Japan and our research has suggested that TFLV is a useful model for studying pathogenic orthonairoviruses. In this study, we successfully established a reverse genetics system for TFLV using T7 RNA polymerase. Recombinant TFLV was generated by transfecting cloned complementary DNAs encoding the TFLV genome into BSR T7/5 cells expressing T7 RNA polymerase. We were able to rescue infectious recombinant TFLV mutant (rTFLVmt) and wild-type TFLV (rTFLVpt) viruses, which exhibited indistinguishable growth kinetics in mammalian cells and pathogenicity in A129 mice compared with the authentic virus. Our approach provides a valuable method for establishing reverse genetics system for orthonairoviruses.
Asunto(s)
ADN Complementario , Genética Inversa , Animales , Genética Inversa/métodos , Ratones , ADN Complementario/genética , Línea Celular , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , Clonación Molecular , Proteínas Virales/genética , Proteínas Virales/metabolismo , Nairovirus/genética , Replicación Viral , Genoma ViralRESUMEN
Rickettsia, a genus of obligate intracellular bacteria, includes species that cause significant human diseases. This study challenges previous claims that the Leucine-973 residue in the RNA polymerase beta subunit is the primary determinant of rifampin resistance in Rickettsia. We investigated a previously untested Rickettsia species, R. lusitaniae, from the Transitional group and found it susceptible to rifampin, despite possessing the Leu-973 residue. Interestingly, we observed the conservation of this residue in several rifampin-susceptible species across most Rickettsia phylogenetic groups. Comparative genomics revealed potential alternative resistance mechanisms, including additional amino acid variants that could hinder rifampin binding and genes that could facilitate rifampin detoxification through efflux pumps. Importantly, the evolutionary history of Rickettsia genomes indicates that the emergence of natural rifampin resistance is phylogenetically constrained within the genus, originating from ancient genetic features shared among a unique set of closely related Rickettsia species. Phylogenetic patterns appear to be the most reliable predictors of natural rifampin resistance, which is confined to a distinct monophyletic subclade known as Massiliae. The distinctive features of the RNA polymerase beta subunit in certain untested Rickettsia species suggest that R. raoultii, R. amblyommatis, R. gravesii, and R. kotlanii may also be naturally rifampin-resistant species.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Farmacorresistencia Bacteriana , Filogenia , Rickettsia , Rifampin , Rifampin/farmacología , Rickettsia/genética , Rickettsia/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , ARN Polimerasas Dirigidas por ADN/genética , Antibacterianos/farmacología , Humanos , Pruebas de Sensibilidad Microbiana , Genoma Bacteriano/genéticaRESUMEN
BACKGROUND: In vitro expression involves the utilization of the cellular transcription and translation machinery in an acellular context to produce one or more proteins of interest and has found widespread application in synthetic biology and in pharmaceutical biomanufacturing. Most in vitro expression systems available are active at moderate temperatures, but to screen large libraries of natural or artificial genetic diversity for highly thermostable enzymes or enzyme variants, it is instrumental to enable protein synthesis at high temperatures. OBJECTIVES: Develop an in vitro expression system operating at high temperatures compatible with enzymatic assays and with technologies that enable ultrahigh-throughput protein expression in reduced volumes, such as microfluidic water-in-oil (w/o) droplets. RESULTS: We produced cell-free extracts from Thermus thermophilus for in vitro translation including thermostable enzymatic cascades for energy regeneration and a moderately thermostable RNA polymerase for transcription, which ultimately limited the temperature of protein synthesis. The yield was comparable or superior to other thermostable in vitro expression systems, while the preparation procedure is much simpler and can be suited to different Thermus thermophilus strains. Furthermore, these extracts have enabled in vitro expression in microfluidic droplets at high temperatures for the first time. CONCLUSIONS: Cell-free extracts from Thermus thermophilus represent a simpler alternative to heavily optimized or pure component thermostable in vitro expression systems. Moreover, due to their compatibility with droplet microfluidics and enzyme assays at high temperatures, the reported system represents a convenient gateway for enzyme screening at higher temperatures with ultrahigh-throughput.
Asunto(s)
Biosíntesis de Proteínas , Thermus thermophilus , Transcripción Genética , Thermus thermophilus/genética , Thermus thermophilus/metabolismo , Thermus thermophilus/enzimología , Microfluídica/métodos , Sistema Libre de Células , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , Temperatura , Calor , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genéticaRESUMEN
BACKGROUND: Poxviruses comprise a group of large double-stranded DNA viruses and are known to cause diseases in humans, livestock animals, and other animal species. The Mpox virus (MPXV; formerly Monkeypox), variola virus (VARV), and volepox virus (VPXV) are among the prevalent poxviruses of the Orthopoxviridae genera. The ongoing Mpox infectious disease pandemic caused by the Mpox virus has had a major impact on public health across the globe. To date, only limited repurposed antivirals and vaccines are available for the effective treatment of Mpox and other poxviruses that cause contagious diseases. METHODS: The present study was conducted with the primary goal of formulating multi-epitope vaccines against three evolutionary closed poxviruses i.e., MPXV, VARV, and VPXV using an integrated immunoinformatics and molecular modeling approach. DNA-dependent RNA polymerase (DdRp), a potential vaccine target of poxviruses, has been used to determine immunodominant B and T-cell epitopes followed by interactions analysis with Toll-like receptor 2 at the atomic level. RESULTS: Three multi-epitope vaccine constructs, namely DdRp_MPXV (V1), DdRp_VARV (V2), and DdRp_VPXV (V3) were designed. These vaccine constructs were found to be antigenic, non-allergenic, non-toxic, and soluble with desired physicochemical properties. Protein-protein docking and interaction profiling analysis depicts a strong binding pattern between the targeted immune receptor TLR2 and the structural models of the designed vaccine constructs, and manifested a number of biochemical bonds (hydrogen bonds, salt bridges, and non-bonded contacts). State-of-the-art all-atoms molecular dynamics simulations revealed highly stable interactions of vaccine constructs with TLR2 at the atomic level throughout the simulations on 300 nanoseconds. Additionally, the outcome of the immune simulation analysis suggested that designed vaccines have the potential to induce protective immunity against targeted poxviruses. CONCLUSIONS: Taken together, formulated next-generation polyvalent vaccines were found to have good efficacy against closely related poxviruses (MPXV, VARV, and VPXV) as demonstrated by our extensive immunoinformatics and molecular modeling evaluations; however, further experimental investigations are still needed.
Asunto(s)
Biología Computacional , Epítopos de Linfocito T , Poxviridae , Vacunas Virales , Vacunas Virales/inmunología , Poxviridae/inmunología , Poxviridae/genética , Biología Computacional/métodos , Epítopos de Linfocito T/inmunología , ARN Polimerasas Dirigidas por ADN/inmunología , ARN Polimerasas Dirigidas por ADN/química , ARN Polimerasas Dirigidas por ADN/genética , Modelos Moleculares , Animales , Humanos , Infecciones por Poxviridae/prevención & control , Infecciones por Poxviridae/inmunología , Infecciones por Poxviridae/virología , Epítopos de Linfocito B/inmunología , Simulación del Acoplamiento Molecular , InmunoinformáticaRESUMEN
Bacteriophage RNA polymerases, in particular T7 RNA polymerase (RNAP), are well-characterized and popular enzymes for many RNA applications in biotechnology both in vitro and in cellular settings. These monomeric polymerases are relatively inexpensive and have high transcription rates and processivity to quickly produce large quantities of RNA. T7 RNAP also has high promoter-specificity on double-stranded DNA (dsDNA) such that it only initiates transcription downstream of its 17-base promoter site on dsDNA templates. However, there are many promoter-independent T7 RNAP transcription reactions involving transcription initiation in regions of single-stranded DNA (ssDNA) that have been reported and characterized. These promoter-independent transcription reactions are important to consider when using T7 RNAP transcriptional systems for DNA nanotechnology and DNA computing applications, in which ssDNA domains often stabilize, organize, and functionalize DNA nanostructures and facilitate strand displacement reactions. Here we review the existing literature on promoter-independent transcription by bacteriophage RNA polymerases with a specific focus on T7 RNAP, and provide examples of how promoter-independent reactions can disrupt the functionality of DNA strand displacement circuit components and alter the stability and functionality of DNA-based materials. We then highlight design strategies for DNA nanotechnology applications that can mitigate the effects of promoter-independent T7 RNAP transcription. The design strategies we present should have an immediate impact by increasing the rate of success of using T7 RNAP for applications in DNA nanotechnology and DNA computing.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , ADN , Nanoestructuras , Regiones Promotoras Genéticas , Transcripción Genética , Proteínas Virales , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , Proteínas Virales/metabolismo , Proteínas Virales/genética , Nanoestructuras/química , ADN/metabolismo , ADN/genética , ADN/química , ADN de Cadena Simple/genética , ADN de Cadena Simple/metabolismo , ADN de Cadena Simple/química , Nanotecnología/métodos , Bacteriófago T7/genéticaRESUMEN
In growing E. coli cells, the transcription-translation complexes (TTCs) form characteristic foci; however, the exact molecular composition of these superstructures is not known with certainty. Herein, we report that, during our recently developed "fast" procedures for purification of E. coli RNA polymerase (RP), a fraction of the RP's α/RpoA subunits is displaced from the core RP complexes and copurifies with multiprotein superstructures carrying the nucleic acid-binding protein Hfq and the ribosomal protein S6. We show that the main components of these large multiprotein assemblies are fixed protein copy-number (Hfq6)n≥8 complexes; these complexes have a high level of structural uniformity and are distinctly unlike the previously described (Hfq6)n "head-to-tail" polymers. We describe purification of these novel, structurally uniform (Hfq6)n≥8 complexes to near homogeneity and show that they also contain small nonprotein molecules and accessory S6. We demonstrate that Hfq, S6, and RP have similar solubility profiles and present evidence pointing to a role of the Hfq C-termini in superstructure formation. Taken together, our data offer new insights into the composition of the macromolecular assemblies likely acting as scaffolds for transcription complexes and ribosomes during bacterial cells' active growth.
Asunto(s)
ARN Polimerasas Dirigidas por ADN , Proteínas de Escherichia coli , Escherichia coli , Transcripción Genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/aislamiento & purificación , Escherichia coli/genética , Escherichia coli/metabolismo , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/química , ARN Polimerasas Dirigidas por ADN/genética , Proteína de Factor 1 del Huésped/metabolismo , Proteína de Factor 1 del Huésped/química , Proteína de Factor 1 del Huésped/genética , Biosíntesis de Proteínas , Complejos Multiproteicos/química , Complejos Multiproteicos/genética , Complejos Multiproteicos/aislamiento & purificación , Complejos Multiproteicos/metabolismoRESUMEN
In flowering plants, euchromatic transposons are transcriptionally silenced by RNA-directed DNA Methylation, a small RNA-guided de novo methylation pathway. RNA-directed DNA Methylation requires the activity of the RNA Polymerases IV and V, which produce small RNA precursors and noncoding targets of small RNAs, respectively. These polymerases are distinguished from Polymerase II by multiple plant-specific paralogous subunits. Most RNA-directed DNA Methylation components are present in all land plants, and some have been found in the charophytic green algae, a paraphyletic group that is sister to land plants. However, the evolutionary origin of key RNA-directed DNA Methylation components, including the two largest subunits of Polymerase IV and Polymerase V, remains unclear. Here, we show that multiple lineages of charophytic green algae encode a single-copy precursor of the largest subunits of Polymerase IV and Polymerase V, resolving the two presumed duplications in this gene family. We further demonstrate the presence of a Polymerase V-like C-terminal domain, suggesting that the earliest form of RNA-directed DNA Methylation utilized a single Polymerase V-like polymerase. Finally, we reveal that charophytic green algae encode a single CLSY/DRD1-type chromatin remodeling protein, further supporting the presence of a single specialized polymerase in charophytic green algae.
Asunto(s)
Metilación de ADN , ARN Polimerasas Dirigidas por ADN , Evolución Molecular , ARN Polimerasas Dirigidas por ADN/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , Filogenia , Carofíceas/genética , Carofíceas/enzimología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Chlorophyta/genética , Chlorophyta/enzimología , Subunidades de Proteína/genéticaRESUMEN
The removal of double-stranded RNA (dsRNA) contaminants during in vitro mRNA synthesis is one of the technological problems to be solved. Apparently, these contaminants are the result of the T7 RNA polymerase side activity. In this study, we used a modified method of mRNA purification based on the selective binding of dsRNA to cellulose in ethanol-containing buffer. It was shown both in vivo and in vitro that the cellulose-purified mRNA preparation leads neither to activation of the lymphocyte inflammatory marker CD69 nor to increased release of IFNα in mice, and does not contain impurities detectable by antibodies to dsRNA.
Asunto(s)
ARN Bicatenario , ARN Mensajero , Animales , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Bicatenario/genética , ARN Bicatenario/metabolismo , Ratones , Antígenos de Diferenciación de Linfocitos T/metabolismo , Antígenos de Diferenciación de Linfocitos T/genética , Antígenos CD/genética , Antígenos CD/metabolismo , Lectinas Tipo C/metabolismo , Lectinas Tipo C/genética , ARN Polimerasas Dirigidas por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/genética , Interferón-alfa/genética , Interferón-alfa/metabolismo , Interferón-alfa/biosíntesis , Proteínas Virales/metabolismo , Proteínas Virales/genéticaRESUMEN
Fast growth phenotypes are achieved through optimal transcriptomic allocation, in which cells must balance tradeoffs in resource allocation between diverse functions. One such balance between stress readiness and unbridled growth in E. coli has been termed the fear versus greed (f/g) tradeoff. Two specific RNA polymerase (RNAP) mutations observed in adaptation to fast growth have been previously shown to affect the f/g tradeoff, suggesting that genetic adaptations may be primed to control f/g resource allocation. Here, we conduct a greatly expanded study of the genetic control of the f/g tradeoff across diverse conditions. We introduced 12 RNA polymerase (RNAP) mutations commonly acquired during adaptive laboratory evolution (ALE) and obtained expression profiles of each. We found that these single RNAP mutation strains resulted in large shifts in the f/g tradeoff primarily in the RpoS regulon and ribosomal genes, likely through modifying RNAP-DNA interactions. Two of these mutations additionally caused condition-specific transcriptional adaptations. While this tradeoff was previously characterized by the RpoS regulon and ribosomal expression, we find that the GAD regulon plays an important role in stress readiness and ppGpp in translation activity, expanding the scope of the tradeoff. A phylogenetic analysis found the greed-related genes of the tradeoff present in numerous bacterial species. The results suggest that the f/g tradeoff represents a general principle of transcriptome allocation in bacteria where small genetic changes can result in large phenotypic adaptations to growth conditions.IMPORTANCETo increase growth, E. coli must raise ribosomal content at the expense of non-growth functions. Previous studies have linked RNAP mutations to this transcriptional shift and increased growth but were focused on only two mutations found in the protein's central region. RNAP mutations, however, commonly occur over a large structural range. To explore RNAP mutations' impact, we have introduced 12 RNAP mutations found in laboratory evolution experiments and obtained expression profiles of each. The mutations nearly universally increased growth rates by adjusting said tradeoff away from non-growth functions. In addition to this shift, a few caused condition-specific adaptations. We explored the prevalence of this tradeoff across phylogeny and found it to be a widespread and conserved trend among bacteria.