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Distinct Responses of Mycobacterium smegmatis to Exposure to Low and High Levels of Hydrogen Peroxide.

ABSTRACT: Hydrogen peroxide (H2O2) is a natural oxidant produced by aerobic organisms and gives rise to oxidative damage, including DNA mutations, protein inactivation and lipid damage. The genus Mycobacterium utilizes redox sensors and H2O2 scavenging enzymes for the detoxification of H2O2. To date, the precise response to oxidative stress has not been fully elucidated. Here, we compared the effects of different levels of H2O2 on transcription in M. smegmatis using RNA-sequencing. A 0.2 mM H2O2 treatment had little effect on the growth and viability of M. smegmatis whereas 7 mM H2O2 was lethal. Analysis of global transcription showed that 0.2 mM H2O2 induced relatively few changes in gene expression, whereas a large proportion of the mycobacterial genome was found to be differentially expressed after treatment with 7 mM H2O2. Genes differentially expressed following treatment with 0.2 mM H2O2 included those coding for proteins involved in glycolysis-gluconeogenesis and fatty acid metabolism pathways, and expression of most genes encoding ribosomal proteins was lower following treatment with 7 mM H2O2. Our analysis shows that M. smegmatis utilizes the sigma factor MSMEG_5214 in response to 0.2 mM H2O2, and the RpoE1 sigma factors MSMEG_0573 and MSMEG_0574 in response to 7 mM H2O2. In addition, different transcriptional regulators responded to different levels of H2O2: MSMEG_1919 was induced by 0.2 mM H2O2, while high-level induction of DevR occurred in response to 7 mM H2O2. We detected the induction of different detoxifying enzymes, including genes encoding KatG, AhpD, TrxB and Trx, at different levels of H2O2 and the detoxifying enzymes were expressed at different levels of H2O2. In conclusion, our study reveals the changes in transcription that are induced in response to different levels of H2O2 in M. smegmatis.

SUBMITTER: Li X

PROVIDER: S-EPMC4520597 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Distinct Responses of Mycobacterium smegmatis to Exposure to Low and High Levels of Hydrogen Peroxide.

Li Xiaojing X Wu Jun J Han Jiao J Hu Yongfei Y Mi Kaixia K

PloS one 20150730 7

Hydrogen peroxide (H2O2) is a natural oxidant produced by aerobic organisms and gives rise to oxidative damage, including DNA mutations, protein inactivation and lipid damage. The genus Mycobacterium utilizes redox sensors and H2O2 scavenging enzymes for the detoxification of H2O2. To date, the precise response to oxidative stress has not been fully elucidated. Here, we compared the effects of different levels of H2O2 on transcription in M. smegmatis using RNA-sequencing. A 0.2 mM H2O2 treatment ...[more]

PMID: 26225431

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Project description:Aliivibrio salmonicida causes âcold-water vibriosisâ (or âHitra diseaseâ) in fish, including marine-reared Atlantic salmon. During development of the disease the bacterium will encounter macrophages with antibacterial activities such as production of damaging reactive oxygen species (ROS). To defend itself the bacterium will presumably start producing detoxifying enzymes, reducing agents, and proteins involved in DNA and protein repair systems. Even though responses to oxidative stress are well studied for a few model bacteria, little work has been done in general to explain how important groups of pathogens, like members of the Vibrionaceae family, can survive at high levels of ROS. We have used bioinformatic tools and an âomics approach to study how A. salmonicida responds to hydrogen peroxide (H2O2). First, we used the recently published genome sequence to predict potential binding sites for OxyR (H2O2 response regulator). The computer-based search identified OxyR sites associated with 20 single genes and 8 operons, and these predictions were compared to experimental data from Northern blot analysis, microarray analysis and 2D gel electrophoresis. In general, OxyR binding site predictions and experimental results are in agreement. Up- and down-regulated genes are distributed among all functional gene categories, but a striking number of â¥2 fold up-regulated genes encode proteins involved in detoxification or DNA protection and repair, are part of reduction systems, or are involved in carbon metabolism and regeneration of NADH/NADPH. Our predictions and âomics data corroborates well with findings from other model bacteria, but also suggest species-specific gene regulation. Two-condition experiment, cells grown in LB medium (control samples) vs. cells grown under oxidative stress (H2O2) (stimulated samples). Samples collected from three different timepoints (15, 30 and 60 min). Technical replicates for each timepoint: 3 control, 3 stimulated, independently grown and harvested. One replicate per array.

Dataset Information

Distinct Responses of Mycobacterium smegmatis to Exposure to Low and High Levels of Hydrogen Peroxide.

Publications

Distinct Responses of Mycobacterium smegmatis to Exposure to Low and High Levels of Hydrogen Peroxide.

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