Dataset Information

Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection.

ABSTRACT: We have used RNASeq and qRT-PCR to study mRNA levels for all ?-factors in different Mycobacterium marinum strains under various growth and stress conditions. We also studied their levels in M. marinum from infected fish and mosquito larvae. The annotated ?-factors were expressed and transcripts varied in relation to growth and stress conditions. Some were highly abundant such as sigA, sigB, sigC, sigD, sigE and sigH while others were not. The ?-factor mRNA profiles were similar after heat stress, during infection of fish and mosquito larvae. The similarity also applies to some of the known heat shock genes such as the ?-crystallin gene. Therefore, it seems probable that the physiological state of M. marinum is similar when exposed to these different conditions. Moreover, the mosquito larvae data suggest that this is the state that the fish encounter when infected, at least with respect to ?-factor mRNA levels. Comparative genomic analysis of ?-factor gene localizations in three M. marinum strains and Mycobacterium tuberculosis H37Rv revealed chromosomal rearrangements that changed the localization of especially sigA, sigB, sigD, sigE, sigF and sigJ after the divergence of these two species. This may explain the variation in species-specific expression upon exposure to different growth conditions.

SUBMITTER: Pettersson BM

PROVIDER: S-EPMC4596819 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection.

Pettersson B M Fredrik BM Das Sarbashis S Behra Phani Rama Krishna PR Jordan Heather R HR Ramesh Malavika M Mallick Amrita A Root Kate M KM Cheramie Martin N MN de la Cruz Melara Irma I Small Pamela L C PL Dasgupta Santanu S Ennis Don G DG Kirsebom Leif A LA

PloS one 20151007 10

We have used RNASeq and qRT-PCR to study mRNA levels for all σ-factors in different Mycobacterium marinum strains under various growth and stress conditions. We also studied their levels in M. marinum from infected fish and mosquito larvae. The annotated σ-factors were expressed and transcripts varied in relation to growth and stress conditions. Some were highly abundant such as sigA, sigB, sigC, sigD, sigE and sigH while others were not. The σ-factor mRNA profiles were similar after heat stress ...[more]

PMID: 26445268

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Project description:Previous studies of the 16S rRNA genes from Mycobacterium ulcerans and Mycobacterium marinum have suggested a very close genetic relationship between these species (99.6% identity). However, these organisms are phenotypically distinct and cause diseases with very different pathologies. To investigate this apparent paradox, we compared 3,306 nucleotides from the partial sequences of eight housekeeping and structural genes derived from 18 M. ulcerans strains and 22 M. marinum strains. This analysis confirmed the close genetic relationship inferred from the 16S rRNA data, with nucleotide sequence identity ranging from 98.1 to 99.7%. The multilocus sequence analysis also confirmed previous genotype studies of M. ulcerans that have identified distinct genotypes within a geographical region. Single isolates of both M. ulcerans and M. marinum that were shown by the sequence analysis to be the most closely related were then selected for further study. One- and two-dimensional pulsed-field gel electrophoresis was employed to compare the architecture and size of the genome from each species. Genome sizes of approximately 4.4 and 4.6 Mb were obtained for M. ulcerans and M. marinum, respectively. Significant macrorestriction fragment polymorphism was observed between the species. However, hybridization analysis of DNA cleaved with more frequently cutting enzymes identified significant preservation of the flanking sequence at seven of the eight loci sequenced. The exception was the 16S rRNA locus. Two high-copy-number insertion sequences, IS2404 and IS2606, have recently been reported in M. ulcerans, and significantly, these elements are not present in M. marinum. Hybridization of the AseI restriction fragments from M. ulcerans with IS2404 and IS2606 indicated widespread genome distribution for both of these repeated sequences. Taken together, these data strongly suggest that M. ulcerans has recently diverged from M. marinum by the acquisition and concomitant loss of DNA in a manner analogous to the emergence of M. tuberculosis, where species diversity is being driven mainly by the activity of mobile DNA elements.

Project description:Listeria monocytogenes is well known to survive and grow under several stress conditions, including salt stress, which is important for growth in certain foods as well as for host infection. To characterize the contributions, to salt stress response, of transcriptional regulators important for stress response and virulence (i.e., σ(B) and PrfA), we analyzed three L. monocytogenes parent strains and isogenic mutants (ΔsigB, ΔprfA, and ΔsigBΔprfA), representing different serotypes and lineages, for their ability to grow, at 25°C, in BHI with 1.9 M NaCl. With regard to growth rate, only the lineage IV strain presented a significant difference between the parent strain and both of its respective mutants lacking prfA (ΔprfA and ΔsigBΔprfA). Conversely, the lineage I and II parent strains showed significantly shorter lag phase in comparison to their respective ΔsigB mutant strains. Intestinal epithelial cell invasion assay and hemolytic activity assays showed a significant role for σ(B) in the former and for PrfA in the latter. To explore the mechanism that may contribute to the extended lag phase in the ΔsigB mutant strain and survival and growth of the parent strain upon salt shock, whole genome transcription profiling was performed to compare transcript levels between the lineage I, serotype 1/2b, parent strain and its isogenic ΔsigB mutant after 30 min of lag phase growth at 25°C in the presence of 1.9M NaCl (salt shock) without aeration. Microarray data showed significantly higher transcript levels for 173 genes in the parent strain as compared to the ΔsigB strain. Overall, 102 of the 173 σ(B) up-regulated genes had been identified in previous studies, indicating that 71 genes were newly identified as being up-regulated by σ(B) in this study. We hypothesize that, among these genes newly identified as σ(B) up-regulated, four genes (lmo2174, lmo0530, lmo0527 and lmo0529) may play a major role in response to salt stress. Lmo2174 contains domains that facilitate sensing and producing a transduction signal in the form of cyclic di-GMP, which may activate the enzymes Lmo0527, Lmo0529 and Lmo0530, which encode proteins similar to those responsible for synthesis of exopolysaccharides that may protect the cell by changing the cell wall structure during salt stress. Overall, our data showed that σ(B), but not PrfA, contributes to growth under salt stress. Moreover, we show that the σ(B) regulon of a L. monocytogenes lineage I strain challenged with salt shock includes salt stress-specific as well as previously unidentified σ(B) up-regulated genes.

Dataset Information

Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection.

Publications

Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection.

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