Mycobacterium tuberculosis H37Ra
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA401651 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR5990232_1.fastq.gz | Fastqsanger.gz | |||
| SRR5990232_2.fastq.gz | Fastqsanger.gz | |||
| SRR5990233_1.fastq.gz | Fastqsanger.gz | |||
| SRR5990233_2.fastq.gz | Fastqsanger.gz | |||
| SRR5990234_1.fastq.gz | Fastqsanger.gz |
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Project description:Previous studies suggest that type I and type II CRISPR-Cas systems were employed to evade host immunity by targeting interference of bacteria’s own genes. Although Mycobacterium bovis (M. bovis) and Mycobacterium tuberculosis (M. tuberculosis) possess integrated type III-A CRISPR-Cas system, its role in mycobacteria remains obscure. Here, we observed that seven cas genes (csm2~6, cas10, cas6) were significantly upregulated under oxidative stress treatment. To explore the function of type III-A CRSIRP-Cas system, Total CRISPR system (TCR) mutant strain was generated in M. bovis Bacille Calmette-Guérin (BCG). Deletion of TCR results in increased sensitivity in response to H2O2 and reduced cell envelope integrity. By using RNA-Seq, 590 differential expression genes were found in mutant for TCR, of which 220 genes were upregulated and 370 genes were downregulated, indicating an important role of TCR in controlling gene expression in mycobacteria. Consistently, disrupting TCR results in poor intracellular survival in vivo and in vitro. Moreover, we showed for the first time that TCR contributed to the regulation of regulatory T cell population, supporting a role of TCR in modulating host immunity. These observations demonstrate that type III-A CRISPR-Cas system as an important factor for intracellular survival and host immunoregulation in mycobacteria, may be a potential target for therapy.
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Project description:Bacteria protect themselves from infection by bacteriophages (phages) using different defence systems, such as CRISPR-Cas. Although CRISPR-Cas provides phage resistance, fitness costs are incurred, such as through autoimmunity. CRISPR-Cas regulation can optimise defence and minimise these costs. We recently developed a genome-wide functional genomics approach (SorTn-seq) for high-throughput discovery of regulators of bacterial gene expression. Here, we applied SorTn-seq to identify loci influencing expression of the two type III-A Serratia CRISPR arrays. Multiple genes affected CRISPR expression, including those involved in outer membrane and lipopolysaccharide synthesis. By comparing loci affecting type III CRISPR arrays and cas operon expression, we identified PigU (LrhA) as a repressor that co-ordinately controls both arrays and cas genes. By repressing type III-A CRISPR-Cas expression, PigU shuts off CRISPR-Cas interference against plasmids and phages. PigU also represses interference and CRISPR adaptation by the type I-F system, which is also present in Serratia. RNA sequencing demonstrated that PigU is a global regulator that controls secondary metabolite production and motility, in addition to CRISPR-Cas immunity. Increased PigU also resulted in elevated expression of three Serratia prophages, indicating their likely induction upon sensing PigU-induced cellular changes. In summary, PigU is a major regulator of CRISPR-Cas immunity in Serratia.
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Project description:In bacteria and archaea, CRISPR loci confer adaptive, sequence-based immunity against viruses and plasmids. CRISPR interference is specified by CRISPR RNAs (crRNAs) that are transcribed and processed from CRISPR spacers and repeats. Pre-crRNA processing is essential for CRISPR interference in all systems studied thus far. Here we examine crRNA biogenesis and CRISPR interference in naturally competent Neisseria spp., including the human pathogen N. meningitidis. Our studies reveal a unique crRNA maturation pathway in which crRNA transcription is driven by promoters that are embedded within each repeat, yielding crRNA 5’ ends are not formed by processing. Although crRNA 3’ end formation occurs through RNase III cleavage of a pre-crRNA/tracrRNA duplex, as in other Type II CRISPR systems, this processing event is dispensable for interference. The meningococcal pathway is the most streamlined CRISPR/cas system characterized to date. Endogenous CRISPR spacers frequently target genomic sequences of other Neisseria strains and so limit natural transformation, which is the primary source of genetic variation that contributes to immune evasion, antibiotic resistance, and virulence in N. meningitidis. dRNA-seq approach for RNA samples from cultures of N. lactamica 020-06, harvested at mid-log. Two cDNA libraries from total RNA were prepared to distinguish between transcripts with either primary orprocessed 5’ ends: one library is generated from untreated RNA, whereas the other is treated with terminator exonuclease (TEX),
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