RESUMO
The series of RNA folding events that occur during transcription can critically influence cellular RNA function. Here, we present reconstructing RNA dynamics from data (R2D2), a method to uncover details of cotranscriptional RNA folding. We model the folding of the Escherichia coli signal recognition particle (SRP) RNA and show that it requires specific local structural fluctuations within a key hairpin to engender efficient cotranscriptional conformational rearrangement into the functional structure. All-atom molecular dynamics simulations suggest that this rearrangement proceeds through an internal toehold-mediated strand-displacement mechanism, which can be disrupted with a point mutation that limits local structural fluctuations and rescued with compensating mutations that restore these fluctuations. Moreover, a cotranscriptional folding intermediate could be cleaved in vitro by recombinant E. coli RNase P, suggesting potential cotranscriptional processing. These results from experiment-guided multi-scale modeling demonstrate that even an RNA with a simple functional structure can undergo complex folding and processing during synthesis.
Assuntos
Proteínas de Escherichia coli/química , Escherichia coli/química , Dobramento de RNA , RNA Bacteriano/química , Ribonuclease P/química , Partícula de Reconhecimento de Sinal/química , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , RNA Bacteriano/metabolismo , Ribonuclease P/metabolismo , Partícula de Reconhecimento de Sinal/metabolismoRESUMO
RNase P is an essential enzyme that catalyzes removal of the 5' leader from precursor transfer RNAs. The ribonucleoprotein (RNP) form of RNase P is present in all domains of life and comprises a single catalytic RNA (ribozyme) and a variable number of protein cofactors. Recent cryo-electron microscopy structures of representative archaeal and eukaryotic (nuclear) RNase P holoenzymes bound to tRNA substrate/product provide high-resolution detail on subunit organization, topology, and substrate recognition in these large, multisubunit catalytic RNPs. These structures point to the challenges in understanding how proteins modulate the RNA functional repertoire and how the structure of an ancient RNA-based catalyst was reshaped during evolution by new macromolecular associations that were likely necessitated by functional/regulatory coupling.
Assuntos
RNA Catalítico , Ribonuclease P , Microscopia Crioeletrônica , Conformação de Ácido Nucleico , RNA , RNA Catalítico/metabolismo , RNA de Transferência/metabolismo , Ribonuclease P/química , Ribonuclease P/genética , Ribonuclease P/metabolismoRESUMO
SignificanceUnderstanding and treating neurological disorders are global priorities. Some of these diseases are engendered by mutations that cause defects in the cellular synthesis of transfer RNAs (tRNAs), which function as adapter molecules that translate messenger RNAs into proteins. During tRNA biogenesis, ribonuclease P catalyzes removal of the transcribed sequence upstream of the mature tRNA. Here, we focus on a cytoplasmic tRNAArgUCU that is expressed specifically in neurons and, when harboring a particular point mutation, contributes to neurodegeneration in mice. Our results suggest that this mutation favors stable alternative structures that are not cleaved by mouse ribonuclease P and motivate a paradigm that may help to understand the molecular basis for disease-associated mutations in other tRNAs.
Assuntos
Homeostase , Neurônios/metabolismo , Conformação de Ácido Nucleico , RNA de Transferência/metabolismo , Animais , Pareamento de Bases , Córtex Cerebral/enzimologia , Magnésio/metabolismo , Camundongos , Modelos Moleculares , Mutação Puntual , Processamento de Proteína Pós-Traducional , RNA de Transferência/química , RNA de Transferência/genética , Ribonuclease P/isolamento & purificação , Ribonuclease P/metabolismo , Especificidade por SubstratoRESUMO
The high-resolution structures of yeast RNase for mitochondrial RNA processing (MRP), a catalytic ribonucleoprotein (RNP), recently reported by Lan et al. and Perederina et al. illustrate how RNA-mediated selection of alternative protein conformations, sampled during stochastic excursions by polymorphic/metamorphic proteins, enabled RNAs and proteins to mutually influence their functional repertoires and shape RNP evolution.
Assuntos
Precursores de RNA , Ribonucleoproteínas , Endorribonucleases/metabolismo , RNA , Processamento Pós-Transcricional do RNA , RNA Ribossômico , Ribonucleases , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismoRESUMO
Distinct functions mediated by members of the monopolar spindle-one-binder (MOB) family of proteins remain elusive beyond the evolutionarily conserved and well-established roles of MOB1 (MOB1A/B) in regulating tissue homeostasis within the Hippo pathway. Since MOB proteins are adaptors, understanding how they engage in protein-protein interactions and help assemble complexes is essential to define the full scope of their biological functions. To address this, we undertook a proximity-dependent biotin identification approach to define the interactomes of all seven human MOB proteins in HeLa and human embryonic kidney 293 cell lines. We uncovered >200 interactions, of which at least 70% are unreported on BioGrid. The generated dataset reliably recalled the bona fide interactors of the well-studied MOBs. We further defined the common and differential interactome between different MOBs on a subfamily and an individual level. We discovered a unique association between MOB3C and 7 of 10 protein subunits of the RNase P complex, an endonuclease that catalyzes tRNA 5' maturation. As a proof of principle for the robustness of the generated dataset, we validated the specific interaction of MOB3C with catalytically active RNase P by using affinity purification-mass spectrometry and pre-tRNA cleavage assays of MOB3C pulldowns. In summary, our data provide novel insights into the biology of MOB proteins and reveal the first interactors of MOB3C, components of the RNase P complex, and hence an exciting nexus with RNA biology.
Assuntos
Via de Sinalização Hippo , Mapeamento de Interação de Proteínas , Proteínas Serina-Treonina Quinases , Ribonuclease P , Humanos , Células HeLa , Via de Sinalização Hippo/fisiologia , Ribonuclease P/metabolismo , Células HEK293 , Subunidades Proteicas/metabolismoRESUMO
RNase P functions either as a catalytic ribonucleoprotein (RNP) or as an RNA-free polypeptide to catalyse RNA processing, primarily tRNA 5' maturation. To the growing evidence of non-canonical roles for RNase P RNP subunits including regulation of chromatin structure and function, we add here a role for the rice RNase P Rpp30 in innate immunity. This protein (encoded by LOC_Os11g01074) was uncovered as the top hit in yeast two-hybrid assays performed with the rice histone deacetylase HDT701 as bait. We showed that HDT701 and OsRpp30 are localized to the rice nucleus, OsRpp30 expression increased post-infection by Pyricularia oryzae (syn. Magnaporthe oryzae), and OsRpp30 deacetylation coincided with HDT701 overexpression in vivo. Overexpression of OsRpp30 in transgenic rice increased expression of defence genes and generation of reactive oxygen species after pathogen-associated molecular pattern elicitor treatment, outcomes that culminated in resistance to a fungal (P. oryzae) and a bacterial (Xanthomonas oryzae pv. oryzae) pathogen. Knockout of OsRpp30 yielded the opposite phenotypes. Moreover, HA-tagged OsRpp30 co-purified with RNase P pre-tRNA cleavage activity. Interestingly, OsRpp30 is conserved in grass crops, including a near-identical C-terminal tail that is essential for HDT701 binding and defence regulation. Overall, our results suggest that OsRpp30 plays an important role in rice immune response to pathogens and provides a new approach to generate broad-spectrum disease-resistant rice cultivars.
Assuntos
Magnaporthe , Oryza , Xanthomonas , Ascomicetos , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/metabolismo , Doenças das Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Subunidades Proteicas , Ribonuclease PRESUMO
RNase P, an essential housekeeping endonuclease needed for 5'-processing of tRNAs, exists in two distinct forms: one with an RNA- and the other with a protein-based active site. The notion that the protein form of RNase P exists only in eukaryotes has been upended by the recent discovery of a protein-only variant in Bacteria and Archaea. The use of these two divergent scaffolds, shaped by convergent evolution, in all three domains of life inspires questions relating to the ancestral form of RNase P, as well as their origins and function(s) in vivo. Results from our analysis of publicly available bacterial and archaeal genomes suggest that the widespread RNA-based ribonucleoprotein variant is likely the ancient form. We also discuss the possible genetic origins and function of RNase P, including how the simultaneous presence of its variants may contribute to the fitness of their host organisms.
Assuntos
Ribonuclease P/genética , Ribonuclease P/metabolismo , Archaea/classificação , Archaea/genética , Archaea/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Evolução Biológica , Ativação Enzimática , Transferência Genética Horizontal , Ribonucleoproteínas/metabolismo , Especificidade da EspécieRESUMO
Identifying the spatial distribution and magnitude of seepage flux across the groundwater-surface water (GW-SW) interface is critical for assessing potential impairments and restoration alternatives for water bodies adjacent to sites with groundwater contamination. Measurement of the vertical distribution and time-varying characteristics of temperature in sediments provides an indirect way to map out spatial and temporal patterns of seepage flux into surface water. Two spreadsheet-based calculation tools are introduced that implement four one-dimensional analytical solutions to calculate the magnitude and direction of seepage flux based on measurement of steady-state vertical temperature profiles or transient diel temperature signals at two depths within sediment. Performance of these calculation tools is demonstrated for a pond receiving contaminated groundwater discharge from an adjacent landfill. Transient versus steady-state model performance is compared, and limitations of transient modelsare illustrated for a situation with unfavorable sediment characteristics and inadequate sensor spacing. The availability of a range of analytical solutions implemented within Microsoft Excel® is intended to encourage practitioners to explore use of this seepage flux characterization method and develop greater insight into best practices for model selection and use.
RESUMO
RNase P is primarily responsible for the 5Î maturation of transfer RNAs (tRNAs) in all domains of life. Archaeal RNase P is a ribonucleoprotein made up of one catalytic RNA and five protein cofactors including L7Ae, which is known to bind the kink-turn (K-turn), an RNA structural element that causes axial bending. However, the number and location of K-turns in archaeal RNase P RNAs (RPRs) are unclear. As part of an integrated approach, we used native mass spectrometry to assess the number of L7Ae copies that bound the RPR and site-specific hydroxyl radical-mediated footprinting to localize the K-turns. Mutagenesis of each of the putative K-turns singly or in combination decreased the number of bound L7Ae copies, and either eliminated or changed the L7Ae footprint on the mutant RPRs. In addition, our results support an unprecedented 'double K-turn' module in type A and type M archaeal RPR variants.
Assuntos
Proteínas Arqueais/química , Regulação da Expressão Gênica em Archaea , Methanocaldococcus/enzimologia , Pyrococcus furiosus/enzimologia , RNA Arqueal/química , RNA de Transferência/química , Ribonuclease P/química , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Sequência de Bases , Radical Hidroxila/química , Radical Hidroxila/metabolismo , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Methanocaldococcus/genética , Mathanococcus/enzimologia , Mathanococcus/genética , Mutação , Conformação de Ácido Nucleico , Ligação Proteica , Pyrococcus furiosus/genética , Precursores de RNA , RNA Arqueal/genética , RNA Arqueal/metabolismo , RNA de Transferência/genética , RNA de Transferência/metabolismo , Ribonuclease P/genética , Ribonuclease P/metabolismoRESUMO
Ribonuclease P (RNase P) is an essential enzyme required for 5'-maturation of tRNA. While an RNA-free, protein-based form of RNase P exists in eukaryotes, the ribonucleoprotein (RNP) form is found in all domains of life. The catalytic component of the RNP is an RNA known as RNase P RNA (RPR). Eukaryotic RPR genes are typically transcribed by RNA polymerase III (pol III). Here we showed that the RPR gene in Drosophila, which is annotated in the intron of a pol II-transcribed protein-coding gene, lacks signals for transcription by pol III. Using reporter gene constructs that include the RPR-coding intron from Drosophila, we found that the intron contains all the sequences necessary for production of mature RPR but is dependent on the promoter of the recipient gene for expression. We also demonstrated that the intron-coded RPR copurifies with RNase P and is required for its activity. Analysis of RPR genes in various animal genomes revealed a striking divide in the animal kingdom that separates insects and crustaceans into a single group in which RPR genes lack signals for independent transcription and are embedded in different protein-coding genes. Our findings provide evidence for a genetic event that occurred approximately 500 million years ago in the arthropod lineage, which switched the control of the transcription of RPR from pol III to pol II.
Assuntos
Drosophila/genética , Evolução Molecular , RNA Catalítico/genética , Ribonuclease P/genética , Animais , Crustáceos/genética , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Genômica , Íntrons/genética , Regiões Promotoras Genéticas , RNA Polimerase III/genética , RNA de Transferência/genéticaRESUMO
The RNA-binding protein L7Ae, known for its role in translation (as part of ribosomes) and RNA modification (as part of sn/oRNPs), has also been identified as a subunit of archaeal RNase P, a ribonucleoprotein complex that employs an RNA catalyst for the Mg(2+)-dependent 5' maturation of tRNAs. To better understand the assembly and catalysis of archaeal RNase P, we used a site-specific hydroxyl radical-mediated footprinting strategy to pinpoint the binding sites of Pyrococcus furiosus (Pfu) L7Ae on its cognate RNase P RNA (RPR). L7Ae derivatives with single-Cys substitutions at residues in the predicted RNA-binding interface (K42C/C71V, R46C/C71V, V95C/C71V) were modified with an iron complex of EDTA-2-aminoethyl 2-pyridyl disulfide. Upon addition of hydrogen peroxide and ascorbate, these L7Ae-tethered nucleases were expected to cleave the RPR at nucleotides proximal to the EDTA-Fe-modified residues. Indeed, footprinting experiments with an enzyme assembled with the Pfu RPR and five protein cofactors (POP5, RPP21, RPP29, RPP30 and L7Ae-EDTA-Fe) revealed specific RNA cleavages, localizing the binding sites of L7Ae to the RPR's catalytic and specificity domains. These results support the presence of two kink-turns, the structural motifs recognized by L7Ae, in distinct functional domains of the RPR and suggest testable mechanisms by which L7Ae contributes to RNase P catalysis.
Assuntos
Proteínas Arqueais/química , Pyrococcus furiosus , RNA Arqueal/química , Proteínas de Ligação a RNA/química , Ribonuclease P/química , Substituição de Aminoácidos , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Sítios de Ligação , Conformação de Ácido Nucleico , Estrutura Secundária de Proteína , Pyrococcus furiosus/genética , RNA Arqueal/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Ribonuclease P/metabolismoRESUMO
RNase P, which catalyzes tRNA 5'-maturation, typically comprises a catalytic RNase P RNA (RPR) and a varying number of RNase P proteins (RPPs): 1 in bacteria, at least 4 in archaea and 9 in eukarya. The four archaeal RPPs have eukaryotic homologs and function as heterodimers (POP5â¢RPP30 and RPP21â¢RPP29). By studying the archaeal Methanocaldococcus jannaschii RPR's cis cleavage of precursor tRNA(Gln) (pre-tRNA(Gln)), which lacks certain consensus structures/sequences needed for substrate recognition, we demonstrate that RPP21â¢RPP29 and POP5â¢RPP30 can rescue the RPR's mis-cleavage tendency independently by 4-fold and together by 25-fold, suggesting that they operate by distinct mechanisms. This synergistic and preferential shift toward correct cleavage results from the ability of archaeal RPPs to selectively increase the RPR's apparent rate of correct cleavage by 11,140-fold, compared to only 480-fold for mis-cleavage. Moreover, POP5â¢RPP30, like the bacterial RPP, helps normalize the RPR's rates of cleavage of non-consensus and consensus pre-tRNAs. We also show that archaeal and eukaryal RNase P, compared to their bacterial relatives, exhibit higher fidelity of 5'-maturation of pre-tRNA(Gln) and some of its mutant derivatives. Our results suggest that protein-rich RNase P variants might have evolved to support flexibility in substrate recognition while catalyzing efficient, high-fidelity 5'-processing.
Assuntos
Archaea/enzimologia , Proteínas Arqueais/metabolismo , Processamento Pós-Transcricional do RNA , RNA de Transferência de Glutamina/metabolismo , Ribonuclease P/metabolismo , Bactérias/enzimologia , Eucariotos/enzimologia , Conformação de Ácido Nucleico , Clivagem do RNA , Precursores de RNA/química , Precursores de RNA/metabolismo , RNA Arqueal/química , RNA Arqueal/metabolismo , RNA de Transferência de Glutamina/químicaRESUMO
We demonstrate that surface-induced dissociation (SID) coupled with ion mobility mass spectrometry (IM-MS) is a powerful tool for determining the stoichiometry of a multi-subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg(2+). We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5' maturation. Previous step-wise, Mg(2+)-dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21â RPP29 and POP5â RPP30) revealed functional RNP intermediates enâ route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21â RPP29 and (POP5â RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM-MS in resolving conformational heterogeneity and yielding insights on RNP assembly.
Assuntos
Espectrometria de Massas/métodos , Pyrococcus furiosus/enzimologia , Ribonuclease P/metabolismo , Catálise , Ribonuclease P/químicaRESUMO
Calcium carbonate increases growth, substrate utilization, and acetone-butanol-ethanol (ABE) fermentation by Clostridium beijerinckii NCIMB 8052. Toward an understanding of the basis for these pleiotropic effects, we profiled changes in the C. beijerinckii NCIMB 8052 proteome that occur in response to the addition of CaCO(3). We observed increases in the levels of different heat shock proteins (GrpE and DnaK), sugar transporters, and proteins involved in DNA synthesis, repair, recombination, and replication. We also noted significant decreases in the levels of proteins involved in metabolism, nucleic acid stabilization, sporulation, oxidative and antibiotic stress responses, and signal transduction. We determined that CaCO(3) enhances ABE fermentation due to both its buffering effects and its ability to influence key cellular processes, such as sugar transport, butanol tolerance, and solventogenesis. Moreover, activity assays in vitro for select solventogenic enzymes revealed that part of the underpinning for the CaCO(3)-mediated increase in the level of ABE fermentation stems from the enhanced activity of these catalysts in the presence of Ca(2+). Collectively, these proteomic and biochemical studies provide new insights into the multifactorial basis for the stimulation of ABE fermentation and butanol tolerance in the presence of CaCO(3).
Assuntos
Acetona/metabolismo , Butanóis/metabolismo , Carbonato de Cálcio/metabolismo , Clostridium beijerinckii/química , Clostridium beijerinckii/metabolismo , Etanol/metabolismo , Proteoma/análise , Clostridium beijerinckii/efeitos dos fármacos , Fermentação , Redes e Vias Metabólicas , Proteômica/métodosRESUMO
To the mounting evidence of nonribosomal functions for ribosomal proteins, we now add L7Ae as a subunit of archaeal RNase P, a ribonucleoprotein (RNP) that catalyzes 5'-maturation of precursor tRNAs (pre-tRNAs). We first demonstrate that L7Ae coelutes with partially purified Methanococcus maripaludis (Mma) RNase P activity. After establishing in vitro reconstitution of the single RNA with four previously known protein subunits (POP5, RPP21, RPP29, and RPP30), we show that addition of L7Ae to this RNase P complex increases the optimal reaction temperature and k(cat)/K(m) (by approximately 360-fold) for pre-tRNA cleavage to those observed with partially purified native Mma RNase P. We identify in the Mma RNase P RNA a putative kink-turn (K-turn), the structural motif recognized by L7Ae. The large stimulatory effect of Mma L7Ae on RNase P activity decreases to Assuntos
Proteínas Arqueais/metabolismo
, Mathanococcus/metabolismo
, Ribonuclease P/metabolismo
, Proteínas Ribossômicas/metabolismo
, Sequência de Aminoácidos
, Proteínas Arqueais/química
, Proteínas Arqueais/genética
, Sequência de Bases
, Western Blotting
, Dicroísmo Circular
, Cinética
, Mathanococcus/enzimologia
, Mathanococcus/genética
, Dados de Sequência Molecular
, Estrutura Secundária de Proteína
, Subunidades Proteicas/química
, Subunidades Proteicas/genética
, Subunidades Proteicas/metabolismo
, Precursores de RNA/metabolismo
, Ribonuclease P/química
, Ribonuclease P/genética
, Proteínas Ribossômicas/química
, Proteínas Ribossômicas/genética
, Homologia de Sequência de Aminoácidos
, Temperatura
RESUMO
RNase P RNA is an ancient, nearly universal feature of life. As part of the ribonucleoprotein RNase P complex, the RNA component catalyzes essential removal of 5' leaders in pre-tRNAs. In 2004, Li and Altman computationally identified the RNase P RNA gene in all but three sequenced microbes: Nanoarchaeum equitans, Pyrobaculum aerophilum, and Aquifex aeolicus (all hyperthermophiles) [Li Y, Altman S (2004) RNA 10:1533-1540]. A recent study concluded that N. equitans does not have or require RNase P activity because it lacks 5' tRNA leaders. The "missing" RNase P RNAs in the other two species is perplexing given evidence or predictions that tRNAs are trimmed in both, prompting speculation that they may have developed novel alternatives to 5' pre-tRNA processing. Using comparative genomics and improved computational methods, we have now identified a radically minimized form of the RNase P RNA in five Pyrobaculum species and the related crenarchaea Caldivirga maquilingensis and Vulcanisaeta distributa, all retaining a conventional catalytic domain, but lacking a recognizable specificity domain. We confirmed 5' tRNA processing activity by high-throughput RNA sequencing and in vitro biochemical assays. The Pyrobaculum and Caldivirga RNase P RNAs are the smallest naturally occurring form yet discovered to function as trans-acting precursor tRNA-processing ribozymes. Loss of the specificity domain in these RNAs suggests altered substrate specificity and could be a useful model for finding other potential roles of RNase P. This study illustrates an effective combination of next-generation RNA sequencing, computational genomics, and biochemistry to identify a divergent, formerly undetectable variant of an essential noncoding RNA gene.
Assuntos
Proteínas Arqueais/genética , Pyrobaculum/genética , RNA Arqueal/genética , Ribonuclease P/genética , Proteínas Arqueais/isolamento & purificação , Proteínas Arqueais/metabolismo , Sequência de Bases , Biocatálise , Biologia Computacional/métodos , Eletroforese em Gel de Poliacrilamida , Genoma Arqueal/genética , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Pyrobaculum/classificação , Pyrobaculum/enzimologia , Precursores de RNA/química , Precursores de RNA/genética , Precursores de RNA/metabolismo , RNA Arqueal/metabolismo , RNA Catalítico/genética , RNA Catalítico/metabolismo , RNA de Transferência/química , RNA de Transferência/genética , RNA de Transferência/metabolismo , Ribonuclease P/isolamento & purificação , Ribonuclease P/metabolismo , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Especificidade por SubstratoRESUMO
Co-phase separation of RNAs and RNA-binding proteins drives the biogenesis of ribonucleoprotein granules. RNAs can also undergo phase transitions in the absence of proteins. However, the physicochemical driving forces of protein-free, RNA-driven phase transitions remain unclear. Here we report that various types of RNA undergo phase separation with system-specific lower critical solution temperatures. This entropically driven phase separation is an intrinsic feature of the phosphate backbone that requires Mg2+ ions and is modulated by RNA bases. RNA-only condensates can additionally undergo enthalpically favourable percolation transitions within dense phases. This is enabled by a combination of Mg2+-dependent bridging interactions between phosphate groups and RNA-specific base stacking and base pairing. Phase separation coupled to percolation can cause dynamic arrest of RNAs within condensates and suppress the catalytic activity of an RNase P ribozyme. Our work highlights the need to incorporate RNA-driven phase transitions into models for ribonucleoprotein granule biogenesis.
Assuntos
RNA Catalítico , RNA , Temperatura , Proteínas de Ligação a RNA , Fosfatos , Transição de FaseRESUMO
RNase P catalyzes 5'-maturation of tRNAs. While bacterial RNase P comprises an RNA catalyst and a protein cofactor, the eukaryotic (nuclear) variant contains an RNA and up to ten proteins, all unrelated to the bacterial protein. Unexpectedly, a nuclear-encoded bacterial RNase P protein (RPP) homolog is found in several prasinophyte algae including Ostreococcus tauri. We demonstrate that recombinant O. tauri RPP can functionally reconstitute with bacterial RNase P RNAs (RPRs) but not with O. tauri organellar RPRs, despite the latter's presumed bacterial origins. We also show that O. tauri PRORP, a homolog of Arabidopsis PRORP-1, displays tRNA 5'-processing activity in vitro. We discuss the implications of the striking diversity of RNase P in O. tauri, the smallest known free-living eukaryote.