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1.
Nucleic Acids Res ; 49(W1): W114-W124, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34037798

RESUMO

In molecular biology and genetics, there is a large gap between the ease of data collection and our ability to extract knowledge from these data. Contributing to this gap is the fact that living organisms are complex systems whose emerging phenotypes are the results of multiple complex interactions taking place on various pathways. This demands powerful yet user-friendly pathway analysis tools to translate the now abundant high-throughput data into a better understanding of the underlying biological phenomena. Here we introduce Consensus Pathway Analysis (CPA), a web-based platform that allows researchers to (i) perform pathway analysis using eight established methods (GSEA, GSA, FGSEA, PADOG, Impact Analysis, ORA/Webgestalt, KS-test, Wilcox-test), (ii) perform meta-analysis of multiple datasets, (iii) combine methods and datasets to accurately identify the impacted pathways underlying the studied condition and (iv) interactively explore impacted pathways, and browse relationships between pathways and genes. The platform supports three types of input: (i) a list of differentially expressed genes, (ii) genes and fold changes and (iii) an expression matrix. It also allows users to import data from NCBI GEO. The CPA platform currently supports the analysis of multiple organisms using KEGG and Gene Ontology, and it is freely available at http://cpa.tinnguyen-lab.com.


Assuntos
Expressão Gênica , Software , Doença de Alzheimer/genética , Conjuntos de Dados como Assunto , Ontologia Genética , Humanos , Internet
2.
Bioinformatics ; 35(10): 1753-1759, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30329036

RESUMO

MOTIVATION: To curate and organize expensive spaceflight experiments conducted aboard space stations and maximize the scientific return of investment, while democratizing access to vast amounts of spaceflight related omics data generated from several model organisms. RESULTS: The GeneLab Data System (GLDS) is an open access database containing fully coordinated and curated 'omics' (genomics, transcriptomics, proteomics, metabolomics) data, detailed metadata and radiation dosimetry for a variety of model organisms. GLDS is supported by an integrated data system allowing federated search across several public bioinformatics repositories. Archived datasets can be queried using full-text search (e.g. keywords, Boolean and wildcards) and results can be sorted in multifactorial manner using assistive filters. GLDS also provides a collaborative platform built on GenomeSpace for sharing files and analyses with collaborators. It currently houses 172 datasets and supports standard guidelines for submission of datasets, MIAME (for microarray), ENCODE Consortium Guidelines (for RNA-seq) and MIAPE Guidelines (for proteomics). AVAILABILITY AND IMPLEMENTATION: https://genelab.nasa.gov/.


Assuntos
Voo Espacial , Biologia Computacional , Bases de Dados Factuais , Genômica
3.
Genome Res ; 26(8): 1069-80, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27260477

RESUMO

Eukaryotic genomes are organized into chromatin domains with three-dimensional arrangements that presumably result from interactions between the chromatin constituents-proteins, DNA, and RNA-within the physical constraints of the nucleus. We used chromosome conformation capture (3C) followed by high-throughput sequencing (Hi-C) with wild-type and mutant strains of Neurospora crassa to gain insight into the role of heterochromatin in the organization and function of the genome. We tested the role of three proteins thought to be important for establishment of heterochromatin, namely, the histone H3 lysine 9 methyltransferase DIM-5, Heterochromatin Protein 1 (HP1), which specifically binds to the product of DIM-5 (trimethylated H3 lysine 9 [H3K9me3]), and DIM-3 (importin alpha), which is involved in DIM-5 localization. The average genome configuration of the wild-type strain revealed strong intra- and inter-chromosomal associations between both constitutive and facultative heterochromatic domains, with the strongest interactions among the centromeres, subtelomeres, and interspersed heterochromatin. Surprisingly, loss of either H3K9me3 or HP1 had only mild effects on heterochromatin compaction, whereas dim-3 caused more drastic changes, specifically decreasing interactions between constitutive heterochromatic domains. Thus, associations between heterochromatic regions are a major component of the chromosome conformation in Neurospora, but two widely studied key heterochromatin proteins are not necessary, implying that undefined protein factors play key roles in maintaining overall chromosome organization.


Assuntos
Proteínas Cromossômicas não Histona/genética , Metilação de DNA/genética , Heterocromatina/genética , Histona-Lisina N-Metiltransferase/genética , alfa Carioferinas/genética , Centrômero/genética , Cromatina/genética , Homólogo 5 da Proteína Cromobox , Genoma Fúngico , Neurospora crassa/genética
4.
Proc Natl Acad Sci U S A ; 113(52): 15048-15053, 2016 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-27856763

RESUMO

High-throughput chromosome conformation capture (Hi-C) analyses revealed that the 3D structure of the Neurospora crassa genome is dominated by intra- and interchromosomal links between regions of heterochromatin, especially constitutive heterochromatin. Elimination of trimethylation of lysine 9 on histone H3 (H3K9me3) or its binding partner Heterochromatin Protein 1 (HP1)-both prominent features of constitutive heterochromatin-have little effect on the Hi-C pattern. It remained possible that di- or trimethylation of lysine 27 on histone H3 (H3K27me2/3), which becomes localized in regions of constitutive heterochromatin when H3K9me3 or HP1 are lost, plays a critical role in the 3D structure of the genome. We found that H3K27me2/3, catalyzed by the Polycomb Repressive Complex 2 (PRC2) member SET-7 (SET domain protein-7), does indeed play a prominent role in the Hi-C pattern of WT, but that its presence in regions normally occupied by H3K9me3 is not responsible for maintenance of the genome architecture when H3K9me3 is lost. The Hi-C pattern of a mutant defective in the PRC2 member N. crassa p55 (NPF), which is predominantly required for subtelomeric H3K27me2/3, was equivalent to that of the set-7 deletion strain, suggesting that subtelomeric facultative heterochromatin is paramount for normal chromosome conformation. Both PRC2 mutants showed decreased heterochromatin-heterochromatin contacts and increased euchromatin-heterochromatin contacts. Cytological observations suggested elimination of H3K27me2/3 leads to partial displacement of telomere clusters from the nuclear periphery. Transcriptional profiling of Δdim-5, Δset-7, Δset-7; Δdim-5, and Δnpf strains detailed anticipated changes in gene expression but did not support the idea that global changes in genome architecture, per se, led to altered transcription.


Assuntos
Cromossomos/ultraestrutura , Heterocromatina/química , Neurospora crassa/metabolismo , Homólogo 5 da Proteína Cromobox , Proteínas Cromossômicas não Histona , Citosina/metabolismo , Metilação de DNA , DNA Fúngico/genética , Proteínas Fúngicas/metabolismo , Perfilação da Expressão Gênica , Inativação Gênica , Genoma Fúngico , Histonas/metabolismo , Lisina/metabolismo , Conformação Molecular , Neurospora crassa/genética , Conformação de Ácido Nucleico , Análise de Sequência de RNA , Telômero/ultraestrutura
5.
Int J Mol Sci ; 20(17)2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31443374

RESUMO

Spaceflight poses many challenges for humans. Ground-based analogs typically focus on single parameters of spaceflight and their associated acute effects. This study assesses the long-term transcriptional effects following single and combination spaceflight analog conditions using the mouse model: simulated microgravity via hindlimb unloading (HLU) and/or low-dose γ-ray irradiation (LDR) for 21 days, followed by 4 months of readaptation. Changes in gene expression and epigenetic modifications in brain samples during readaptation were analyzed by whole transcriptome shotgun sequencing (RNA-seq) and reduced representation bisulfite sequencing (RRBS). The results showed minimal gene expression and cytosine methylation alterations at 4 months readaptation within single treatment conditions of HLU or LDR. In contrast, following combined HLU+LDR, gene expression and promoter methylation analyses showed multiple altered pathways involved in neurogenesis and neuroplasticity, the regulation of neuropeptides, and cellular signaling. In brief, neurological readaptation following combined chronic LDR and HLU is a dynamic process that involves pathways that regulate neuronal function and structure and may lead to late onset neurological sequelae.


Assuntos
Suscetibilidade a Doenças , Doenças do Sistema Nervoso/etiologia , Doses de Radiação , Radiação Ionizante , Ausência de Peso , Animais , Biomarcadores , Peso Corporal , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Metilação de DNA , Modelos Animais de Doenças , Exposição Ambiental/efeitos adversos , Feminino , Raios gama , Perfilação da Expressão Gênica , Camundongos , Doenças do Sistema Nervoso/metabolismo , Regiões Promotoras Genéticas , Transdução de Sinais , Transcriptoma , Simulação de Ausência de Peso
6.
Biotechnol Bioeng ; 115(9): 2305-2314, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29896914

RESUMO

The oxygenic photosynthetic bacterium Synechocystis sp. PCC 6803 (S6803) is a model cyanobacterium widely used for fundamental research and biotechnology applications. Due to its polyploidy, existing methods for genome engineering of S6803 require multiple rounds of selection to modify all genome copies, which is time-consuming and inefficient. In this study, we engineered the Cas9 tool for one-step, segregation-free genome engineering. We further used our Cas9 tool to delete three of seven S6803 native plasmids. Our results show that all three small-size native plasmids, but not the large-size native plasmids, can be deleted with this tool. To further facilitate heterologous gene expression in S6803, a shuttle vector based on the native plasmid pCC5.2 was created. The shuttle vector can be introduced into Cas9-containing S6803 in one step without requiring segregation and can be stably maintained without antibiotic pressure for at least 30 days. Moreover, genes encoded on the shuttle vector remain functional after 30 days of continuous cultivation without selective pressure. Thus, this study provides a set of new tools for rapid modification of the S6803 genome and for stable expression of heterologous genes, potentially facilitating both fundamental research and biotechnology applications using S6803.


Assuntos
Proteína 9 Associada à CRISPR/metabolismo , Edição de Genes/métodos , Vetores Genéticos , Genética Microbiana/métodos , Plasmídeos , Synechocystis/genética , Expressão Gênica , Instabilidade Genômica , Recombinação Genética
7.
Biomacromolecules ; 19(9): 3853-3860, 2018 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-30080972

RESUMO

Despite significant efforts to engineer their heterologous production, recombinant spider silk proteins (spidroins) have yet to replicate the unparalleled combination of high strength and toughness exhibited by natural spider silks, preventing their use in numerous mechanically demanding applications. To overcome this long-standing challenge, we have developed a synthetic biology approach combining standardized DNA part assembly and split intein-mediated ligation to produce recombinant spidroins of previously unobtainable size (556 kDa), containing 192 repeat motifs of the Nephila clavipes dragline spidroin. Fibers spun from our synthetic spidroins are the first to fully replicate the mechanical performance of their natural counterparts by all common metrics, i.e., tensile strength (1.03 ± 0.11 GPa), modulus (13.7 ± 3.0 GPa), extensibility (18 ± 6%), and toughness (114 ± 51 MJ/m3). The developed process reveals a path to more dependable production of high-performance silks for mechanically demanding applications while also providing a platform to facilitate production of other high-performance natural materials.


Assuntos
Fibroínas/química , Resistência à Tração , Elasticidade , Fibroínas/genética , Fibroínas/normas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética
8.
J Biol Chem ; 289(5): 2610-9, 2014 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-24344125

RESUMO

Neurospora crassa colonizes burnt grasslands and metabolizes both cellulose and hemicellulose from plant cell walls. When switched from a favored carbon source to cellulose, N. crassa dramatically up-regulates expression and secretion of genes encoding lignocellulolytic enzymes. However, the means by which N. crassa and other filamentous fungi sense the presence of cellulose in the environment remains unclear. Previously, we have shown that a N. crassa mutant carrying deletions of three ß-glucosidase enzymes (Δ3ßG) lacks ß-glucosidase activity, but efficiently induces cellulase gene expression and cellulolytic activity in the presence of cellobiose as the sole carbon source. These observations indicate that cellobiose, or a modified version of cellobiose, functions as an inducer of lignocellulolytic gene expression and activity in N. crassa. Here, we show that in N. crassa, two cellodextrin transporters, CDT-1 and CDT-2, contribute to cellulose sensing. A N. crassa mutant carrying deletions for both transporters is unable to induce cellulase gene expression in response to crystalline cellulose. Furthermore, a mutant lacking genes encoding both the ß-glucosidase enzymes and cellodextrin transporters (Δ3ßGΔ2T) does not induce cellulase gene expression in response to cellobiose. Point mutations that severely reduce cellobiose transport by either CDT-1 or CDT-2 when expressed individually do not greatly impact cellobiose induction of cellulase gene expression. These data suggest that the N. crassa cellodextrin transporters act as "transceptors" with dual functions - cellodextrin transport and receptor signaling that results in downstream activation of cellulolytic gene expression. Similar mechanisms of transceptor activity likely occur in related ascomycetes used for industrial cellulase production.


Assuntos
Biocombustíveis/microbiologia , Celobiose/metabolismo , Celulose/análogos & derivados , Celulose/metabolismo , Dextrinas/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Neurospora crassa/metabolismo , Transporte Biológico/fisiologia , Celulase/genética , Celulase/metabolismo , Regulação Fúngica da Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Mutagênese Sítio-Dirigida , Neurospora crassa/genética , Neurospora crassa/crescimento & desenvolvimento , beta-Glucosidase/genética , beta-Glucosidase/metabolismo
9.
Fungal Genet Biol ; 79: 63-70, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25857259

RESUMO

The presence or absence of specific transcription factors, chromatin remodeling machineries, chromatin modification enzymes, post-translational histone modifications and histone variants all play crucial roles in the regulation of pathogenicity genes. Chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing (ChIP-seq) provides an important tool to study genome-wide protein-DNA interactions to help understand gene regulation in the context of native chromatin. ChIP-seq is a convenient in vivo technique to identify, map and characterize occupancy of specific DNA fragments with proteins against which specific antibodies exist or which can be epitope-tagged in vivo. We optimized existing ChIP protocols for use in the wheat pathogen Zymoseptoria tritici and closely related sister species. Here, we provide a detailed method, underscoring which aspects of the technique are organism-specific. Library preparation for Illumina sequencing is described, as this is currently the most widely used ChIP-seq method. One approach for the analysis and visualization of representative sequence is described; improved tools for these analyses are constantly being developed. Using ChIP-seq with antibodies against H3K4me2, which is considered a mark for euchromatin or H3K9me3 and H3K27me3, which are considered marks for heterochromatin, the overall distribution of euchromatin and heterochromatin in the genome of Z. tritici can be determined. Our ChIP-seq protocol was also successfully applied to Z. tritici strains with high levels of melanization or aberrant colony morphology, and to different species of the genus (Z. ardabiliae and Z. pseudotritici), suggesting that our technique is robust. The methods described here provide a powerful framework to study new aspects of chromatin biology and gene regulation in this prominent wheat pathogen.


Assuntos
Ascomicetos/genética , Imunoprecipitação da Cromatina , DNA Fúngico/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Proteínas de Ligação a DNA/genética , Proteínas Fúngicas/genética , Doenças das Plantas/microbiologia , Triticum/microbiologia
10.
Appl Microbiol Biotechnol ; 98(3): 1087-94, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24190499

RESUMO

Saccharomyces cerevisiae can be engineered to ferment cellodextrins produced by cellulases as a product of cellulose hydrolysis. Direct fermentation of cellodextrins instead of glucose is advantageous because glucose inhibits cellulase activity and represses the fermentation of non-glucose sugars present in cellulosic hydrolyzates. To facilitate cellodextrin utilization by S. cerevisiae, a fungal cellodextrin-utilizing pathway from Neurospora crassa consisting of a cellodextrin transporter and a cellodextrin hydrolase has been introduced into S. cerevisiae. Two cellodextrin transporters (CDT-1 and CDT-2) were previously identified in N. crassa, but their kinetic properties and efficiency for cellobiose fermentation have not been studied in detail. In this study, CDT-1 and CDT-2, which are hypothesized to transport cellodextrin with distinct mechanisms, were introduced into S. cerevisiae along with an intracellular ß-glucosidase (GH1-1). Cellobiose transport assays with the resulting strains indicated that CDT-1 is a proton symporter while CDT-2 is a simple facilitator. A strain expressing CDT-1 and GH1-1 (DCDT-1G) showed faster cellobiose fermentation than the strain expressing CDT-2 and GH1-1 (DCDT-2G) under various culture conditions with different medium compositions and aeration levels. While CDT-2 is expected to have energetic benefits, the expression levels and kinetic properties of CDT-1 in S. cerevisiae appears to be optimum for cellobiose fermentation. These results suggest CDT-1 is a more effective cellobiose transporter than CDT-2 for engineering S. cerevisiae to ferment cellobiose.


Assuntos
Celobiose/metabolismo , Celulose/análogos & derivados , Dextrinas/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Neurospora crassa/enzimologia , Celulose/metabolismo , Fermentação , Proteínas de Membrana Transportadoras/genética , Neurospora crassa/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
11.
Proc Natl Acad Sci U S A ; 108(2): 504-9, 2011 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-21187422

RESUMO

The use of plant biomass for biofuel production will require efficient utilization of the sugars in lignocellulose, primarily glucose and xylose. However, strains of Saccharomyces cerevisiae presently used in bioethanol production ferment glucose but not xylose. Yeasts engineered to ferment xylose do so slowly, and cannot utilize xylose until glucose is completely consumed. To overcome these bottlenecks, we engineered yeasts to coferment mixtures of xylose and cellobiose. In these yeast strains, hydrolysis of cellobiose takes place inside yeast cells through the action of an intracellular ß-glucosidase following import by a high-affinity cellodextrin transporter. Intracellular hydrolysis of cellobiose minimizes glucose repression of xylose fermentation allowing coconsumption of cellobiose and xylose. The resulting yeast strains, cofermented cellobiose and xylose simultaneously and exhibited improved ethanol yield when compared to fermentation with either cellobiose or xylose as sole carbon sources. We also observed improved yields and productivities from cofermentation experiments performed with simulated cellulosic hydrolyzates, suggesting this is a promising cofermentation strategy for cellulosic biofuel production. The successful integration of cellobiose and xylose fermentation pathways in yeast is a critical step towards enabling economic biofuel production.


Assuntos
Biotecnologia/métodos , Celobiose/metabolismo , Engenharia Genética , Microbiologia Industrial/métodos , Saccharomyces cerevisiae/genética , Xilose/metabolismo , Escherichia coli/genética , Etanol/química , Fermentação , Glucose/metabolismo , Modelos Biológicos , Espectrofotometria Ultravioleta/métodos , Xilose/química
12.
Nat Commun ; 15(1): 4778, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38862479

RESUMO

Impairment of the central nervous system (CNS) poses a significant health risk for astronauts during long-duration space missions. In this study, we employed an innovative approach by integrating single-cell multiomics (transcriptomics and chromatin accessibility) with spatial transcriptomics to elucidate the impact of spaceflight on the mouse brain in female mice. Our comparative analysis between ground control and spaceflight-exposed animals revealed significant alterations in essential brain processes including neurogenesis, synaptogenesis and synaptic transmission, particularly affecting the cortex, hippocampus, striatum and neuroendocrine structures. Additionally, we observed astrocyte activation and signs of immune dysfunction. At the pathway level, some spaceflight-induced changes in the brain exhibit similarities with neurodegenerative disorders, marked by oxidative stress and protein misfolding. Our integrated spatial multiomics approach serves as a stepping stone towards understanding spaceflight-induced CNS impairments at the level of individual brain regions and cell types, and provides a basis for comparison in future spaceflight studies. For broader scientific impact, all datasets from this study are available through an interactive data portal, as well as the National Aeronautics and Space Administration (NASA) Open Science Data Repository (OSDR).


Assuntos
Encéfalo , Neurônios , Voo Espacial , Animais , Camundongos , Feminino , Encéfalo/metabolismo , Encéfalo/patologia , Neurônios/metabolismo , Transcriptoma , Neurogênese , Análise de Célula Única , Camundongos Endogâmicos C57BL , Transmissão Sináptica , Ausência de Peso/efeitos adversos , Astrócitos/metabolismo , Estresse Oxidativo , Perfilação da Expressão Gênica , Multiômica
13.
Metab Eng ; 15: 226-34, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23103205

RESUMO

As Saccharomyces cerevisiae cannot utilize xylose as a carbon source, expression of XYL1 coding for xylose reductase (XR) from Scheffersomyces (Pichia) stipitis enabled production of xylitol from xylose with a high yield. However, insufficient supply of NAD(P)H for XR and inhibition of xylose uptake by glucose are identified as major constraints for achieving high xylitol productivity. To overcome these problems, we engineered S. cerevisiae capable of converting xylose into xylitol through simultaneous utilization of xylose and cellobiose. An engineered S. cerevisiae (D-10-BT) expressing XR, cellodextrin transporter (cdt-1) and intracellular ß-glucosidase (gh1-1) produced xylitol via simultaneous utilization of cellobiose and xylose. The D-10-BT strain exhibited 40% higher volumetric xylitol productivity with co-consumption of cellobiose and xylose compared to sequential utilization of glucose and xylose. Furthermore, the overexpression of S. cerevisiae ALD6, IDP2, or S. stipitis ZWF1 coding for cytosolic NADP(+)-dependent dehydrogenases increased the intracellular NADPH availability of the D-10-BT strain, which resulted in a 37-63% improvement in xylitol productivity when cellobiose and xylose were co-consumed. These results suggest that co-utilization of cellobiose and xylose can lead to improved xylitol production through enhanced xylose uptake and efficient cofactor regeneration.


Assuntos
Celobiose/metabolismo , Ciclodextrinas/genética , Melhoramento Genético/métodos , Saccharomyces cerevisiae/fisiologia , Xilitol/biossíntese , Xilose/metabolismo , beta-Glucosidase/genética , Engenharia Metabólica/métodos , Xilitol/isolamento & purificação
14.
Metab Eng ; 15: 134-43, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23178501

RESUMO

Anaerobic bacteria assimilate cellodextrins from plant biomass by using a phosphorolytic pathway to generate glucose intermediates for growth. The yeast Saccharomyces cerevisiae can also be engineered to ferment cellobiose to ethanol using a cellodextrin transporter and a phosphorolytic pathway. However, strains with an intracellular cellobiose phosphorylase initially fermented cellobiose slowly relative to a strain employing an intracellular ß-glucosidase. Fermentations by the phosphorolytic strains were greatly improved by using cellodextrin transporters with elevated rates of cellobiose transport. Furthermore under stress conditions, these phosphorolytic strains had higher biomass and ethanol yields compared to hydrolytic strains. These observations suggest that, although cellobiose phosphorolysis has energetic advantages, phosphorolytic strains are limited by the thermodynamics of cellobiose phosphorolysis (ΔG°=+3.6kJmol(-1)). A thermodynamic "push" from the reaction immediately upstream (transport) is therefore likely to be necessary to achieve high fermentation rates and energetic benefits of phosphorolysis pathways in engineered S. cerevisiae.


Assuntos
Celobiose/metabolismo , Celulose/análogos & derivados , Dextrinas/metabolismo , Etanol/metabolismo , Melhoramento Genético/métodos , Glucosiltransferases/genética , Saccharomyces cerevisiae/fisiologia , Celulose/genética , Celulose/metabolismo , Dextrinas/genética , Fermentação , Mutagênese Sítio-Dirigida , Engenharia de Proteínas/métodos
15.
Appl Environ Microbiol ; 79(5): 1500-7, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23263959

RESUMO

Saccharomyces cerevisiae cannot utilize cellobiose, but this yeast can be engineered to ferment cellobiose by introducing both cellodextrin transporter (cdt-1) and intracellular ß-glucosidase (gh1-1) genes from Neurospora crassa. Here, we report that an engineered S. cerevisiae strain expressing the putative hexose transporter gene HXT2.4 from Scheffersomyces stipitis and gh1-1 can also ferment cellobiose. This result suggests that HXT2.4p may function as a cellobiose transporter when HXT2.4 is overexpressed in S. cerevisiae. However, cellobiose fermentation by the engineered strain expressing HXT2.4 and gh1-1 was much slower and less efficient than that by an engineered strain that initially expressed cdt-1 and gh1-1. The rate of cellobiose fermentation by the HXT2.4-expressing strain increased drastically after serial subcultures on cellobiose. Sequencing and retransformation of the isolated plasmids from a single colony of the fast cellobiose-fermenting culture led to the identification of a mutation (A291D) in HXT2.4 that is responsible for improved cellobiose fermentation by the evolved S. cerevisiae strain. Substitutions for alanine (A291) of negatively charged amino acids (A291E and A291D) or positively charged amino acids (A291K and A291R) significantly improved cellobiose fermentation. The mutant HXT2.4(A291D) exhibited 1.5-fold higher K(m) and 4-fold higher V(max) values than those from wild-type HXT2.4, whereas the expression levels were the same. These results suggest that the kinetic properties of wild-type HXT2.4 expressed in S. cerevisiae are suboptimal, and mutations of A291 into bulky charged amino acids might transform HXT2.4p into an efficient transporter, enabling rapid cellobiose fermentation by engineered S. cerevisiae strains.


Assuntos
Substituição de Aminoácidos , Celobiose/metabolismo , Engenharia Metabólica , Proteínas de Transporte de Monossacarídeos/genética , Proteínas de Transporte de Monossacarídeos/metabolismo , Saccharomycetales/genética , Saccharomycetales/metabolismo , Análise Mutacional de DNA , Fermentação , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Análise de Sequência de DNA , Inoculações Seriadas
16.
Chromosome Res ; 20(5): 635-56, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22752455

RESUMO

How centromeres are assembled and maintained remains one of the fundamental questions in cell biology. Over the past 20 years, the idea of centromeres as precise genetic loci has been replaced by the realization that it is predominantly the protein complement that defines centromere localization and function. Thus, placement and maintenance of centromeres are excellent examples of epigenetic phenomena in the strict sense. In contrast, the highly derived "point centromeres" of the budding yeast Saccharomyces cerevisiae and its close relatives are counter-examples for this general principle of centromere maintenance. While we have learned much in the past decade, it remains unclear if mechanisms for epigenetic centromere placement and maintenance are shared among various groups of organisms. For that reason, it seems prudent to examine species from many different phylogenetic groups with the aim to extract comparative information that will yield a more complete picture of cell division in all eukaryotes. This review addresses what has been learned by studying the centromeres of filamentous fungi, a large, heterogeneous group of organisms that includes important plant, animal and human pathogens, saprobes, and symbionts that fulfill essential roles in the biosphere, as well as a growing number of taxa that have become indispensable for industrial use.


Assuntos
Centrômero/metabolismo , Cromossomos Fúngicos/metabolismo , Fungos/genética , Sequência de Aminoácidos , Centrômero/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos Fúngicos/genética , DNA Fúngico/genética , DNA Fúngico/metabolismo , Epigênese Genética , Evolução Molecular , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fungos/metabolismo , Histonas/metabolismo , Dados de Sequência Molecular , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Filogenia , Ligação Proteica , Estabilidade Proteica , Relação Estrutura-Atividade
17.
NPJ Microgravity ; 9(1): 66, 2023 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-37587131

RESUMO

The undesirable, yet inevitable, presence of bacterial biofilms in spacecraft poses a risk to the proper functioning of systems and to astronauts' health. To mitigate the risks that arise from them, it is important to understand biofilms' behavior in microgravity. As part of the Space Biofilms project, biofilms of Pseudomonas aeruginosa were grown in spaceflight over material surfaces. Stainless Steel 316 (SS316) and passivated SS316 were tested for their relevance as spaceflight hardware components, while a lubricant impregnated surface (LIS) was tested as potential biofilm control strategy. The morphology and gene expression of biofilms were characterized. Biofilms in microgravity are less robust than on Earth. LIS strongly inhibits biofilm formation compared to SS. Furthermore, this effect is even greater in spaceflight than on Earth, making LIS a promising option for spacecraft use. Transcriptomic profiles for the different conditions are presented, and potential mechanisms of biofilm reduction on LIS are discussed.

18.
NPJ Microgravity ; 9(1): 78, 2023 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-37717090

RESUMO

Space-based biomanufacturing has the potential to improve the sustainability of deep space exploration. To advance biomanufacturing, bioprocessing systems need to be developed for space applications. Here, commercial technologies were assessed to design space bioprocessing systems to supply a liquid amine carbon dioxide scrubber with active carbonic anhydrase produced recombinantly. Design workflows encompassed biomass dewatering of 1 L Escherichia coli cultures through to recombinant protein purification. Non-crew time equivalent system mass (ESM) analyses had limited utility for selecting specific technologies. Instead, bioprocessing system designs focused on minimizing complexity and enabling system versatility. Three designs that differed in biomass dewatering and protein purification approaches had nearly equivalent ESM of 357-522 kg eq. Values from the system complexity metric (SCM), technology readiness level (TRL), integration readiness level (IRL), and degree of crew assistance metric identified a simpler, less costly, and easier to operate design for automated biomass dewatering, cell lysis, and protein affinity purification.

19.
Environ Mol Mutagen ; 63(4): 184-189, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35470505

RESUMO

Ionizing radiation is a well-appreciated health risk, precipitant of DNA damage, and contributor to DNA methylation variability. Nevertheless, relationships of ionizing radiation with DNA methylation-based markers of biological age (i.e. epigenetic clocks) remain poorly understood. Using existing data from human bronchial epithelial cells, we examined in vitro relationships of three epigenetic clock measures (Horvath DNAmAge, MiAge, and epiTOC2) with galactic cosmic radiation (GCR), which is particularly hazardous due to its high linear energy transfer (LET) heavy-ion components. High-LET 56Fe was significantly associated with accelerations in epiTOC2 (ß = 192 cell divisions, 95% CI: 71, 313, p-value = .003). We also observed a significant, positive interaction of 56Fe ions and time-in-culture with epiTOC2 (95% CI: 42, 441, p-value = .019). However, only the direct 56Fe ion association remained statistically significant after adjusting for multiple hypothesis testing. Epigenetic clocks were not significantly associated with high-LET 28Si and low-LET X-rays. Our results demonstrate sensitivities of specific epigenetic clock measures to certain forms of GCR. These findings suggest that epigenetic clocks may have some utility for monitoring and better understanding the health impacts of GCR.


Assuntos
Radiação Cósmica , Radiação Cósmica/efeitos adversos , Epigênese Genética , Epigenômica , Células Epiteliais , Humanos , Transferência Linear de Energia
20.
Cell Rep Methods ; 2(11): 100325, 2022 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-36452864

RESUMO

Single-cell RNA sequencing (scRNA-seq) and spatially resolved transcriptomics (SRT) have experienced rapid development in recent years. The findings of spaceflight-based scRNA-seq and SRT investigations are likely to improve our understanding of life in space and our comprehension of gene expression in various cell systems and tissue dynamics. However, compared to their Earth-based counterparts, gene expression experiments conducted in spaceflight have not experienced the same pace of development. Out of the hundreds of spaceflight gene expression datasets available, only a few used scRNA-seq and SRT. In this perspective piece, we explore the growing importance of scRNA-seq and SRT in space biology and discuss the challenges and considerations relevant to robust experimental design to enable growth of these methods in the field.


Assuntos
Voo Espacial , Transcriptoma , Transcriptoma/genética , Análise de Sequência de RNA/métodos , Análise de Célula Única/métodos , Perfilação da Expressão Gênica/métodos
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