Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Superoxide Generation and Its Involvement in the Growth of Mycobacterium smegmatis.

ABSTRACT: Superoxide generation is inevitable in aerobic organisms, most of which have developed mechanisms to detoxify superoxides. However, its significance has not been clearly understood in mycobacteria. This study demonstrates that NADH oxidase is the major source of superoxide in Mycobacterium smegmatis and elucidates the involvement of superoxide in M. smegmatis growth. The maximum inhibition of superoxide generation was observed in the presence of diphenyleneiodonium chloride (DPI), an NADH oxidase inhibitor, compared to other standard inhibitors. After incubation for 24 h, the number of colony forming units (CFUs) was reduced by 6.8 log10 compared to the untreated culture. The inhibitory effect of DPI on M. smegmatis was reversed when the same culture was supplemented with menadione and pyrogallol, which are superoxide generators. Thus, this study reports the source of superoxide generation and its involvement in the growth of M. smegmatis.

SUBMITTER: Yeware AM

PROVIDER: S-EPMC5276846 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Superoxide Generation and Its Involvement in the Growth of Mycobacterium smegmatis.

Yeware Amar M AM Shurpali Ketaki D KD Athalye Meghana C MC Sarkar Dhiman D

Frontiers in microbiology 20170130

Superoxide generation is inevitable in aerobic organisms, most of which have developed mechanisms to detoxify superoxides. However, its significance has not been clearly understood in mycobacteria. This study demonstrates that NADH oxidase is the major source of superoxide in Mycobacterium smegmatis and elucidates the involvement of superoxide in M. smegmatis growth. The maximum inhibition of superoxide generation was observed in the presence of diphenyleneiodonium chloride (DPI), ...[more]

PMID: 28194149

Similar Datasets

Acanthamoeba polyphaga-enhanced growth of Mycobacterium smegmatis.

Project description:BackgroundMycobacterium smegmatis is a rapidly-growing mycobacterium causing rare opportunistic infections in human patients. It is present in soil and water environments where free-living amoeba also reside, but data regarding M. smegmatis-amoeba relationships have been contradictory from mycobacteria destruction to mycobacteria survival.Methodology/principal findingsUsing optic and electron microscopy and culture-based microbial enumeration we investigated the ability of M. smegmatis mc(2) 155, M. smegmatis ATCC 19420(T) and M. smegmatis ATCC 27204 organisms to survive into Acanthamoeba polyphaga trophozoites and cysts. We observed that M. smegmatis mycobacteria penetrated and survived in A. polyphaga trophozoites over five-day co-culture resulting in amoeba lysis and the release of viable M. smegmatis mycobacteria without amoebal cyst formation. We further observed that amoeba-co-culture, and lysed amoeba and supernatant and pellet, significantly increased five-day growth of the three tested M. smegmatis strains, including a four-fold increase in intra-amoebal growth.Conclusions/significanceAmoebal co-culture increases the growth of M. smegmatis resulting in amoeba killing by replicating M. smegmatis mycobacteria. This amoeba-M. smegmatis co-culture system illustrates an unusual paradigm in the mycobacteria-amoeba interactions as mycobacteria have been mainly regarded as amoeba-resistant organisms. Using these model organisms, this co-culture system could be used as a simple and rapid model to probe mycobacterial factors implicated in the intracellular growth of mycobacteria.

| S-EPMC3256201 | biostudies-literature

Involvement of Holliday junction resolvase in fluoroquinolone-mediated killing of Mycobacterium smegmatis.

Project description:The absence of the Holliday-junction Ruv resolvase of Mycobacterium smegmatis increased the bacteriostatic and bactericidal activities of the fluoroquinolone moxifloxacin, an important antituberculosis agent. The treatment of ruvAB-deficient cells with thiourea and 2,2'-bipyridyl lowered moxifloxacin lethality to wild-type levels, indicating that the absence of ruvAB stimulates a lethal pathway involving reactive oxygen species. A hexapeptide that traps the Holliday junction substrate of RuvAB potentiated moxifloxacin-mediated lethality, supporting the development of small-molecule enhancers for moxifloxacin activity against mycobacteria.

| S-EPMC4325773 | biostudies-literature

Lipoarabinomannan localization and abundance during growth of Mycobacterium smegmatis.

Project description:Lipoarabinomannan (LAM) is a structurally heterogeneous amphipathic lipoglycan present in Mycobacterium spp. and other actinomycetes, which constitutes a major component of the cell wall and exhibits a wide spectrum of immunomodulatory effects. Analysis of Mycobacterium smegmatis subcellular fractions and spheroplasts showed that LAM and lipomannan (LM) were primarily found in a cell wall-enriched subcellular fraction and correlated with the presence (or absence) of the mycolic acids in spheroplast preparations, suggesting that LAM and LM are primarily associated with the putative outer membrane of mycobacteria. During the course of these studies significant changes in the LAM/LM content of the cell wall were noted relative to the age of the culture. The LAM content of the M. smegmatis cell wall was dramatically reduced as the bacilli approached stationary phase, whereas LM, mycolic acid, and arabinogalactan content appeared to be unchanged. In addition, cell morphology and acid-fast staining characteristics showed variations with growth phase of the bacteria. In the logarithmic phase, the bacteria were found to be classic rod-shaped acid-fast bacilli, while in the stationary phase M. smegmatis lost the characteristic rod shape and developed a punctate acid-fast staining pattern with carbolfuchsin. The number of viable bacteria was independent of LAM content and phenotype. Taken together, the results presented here suggest that LAM is primarily localized with the mycolic acids in the cell wall and that the cellular concentration of LAM in M. smegmatis is selectively modulated with the growth phase.

| S-EPMC3187192 | biostudies-literature

Efficient and simple generation of multiple unmarked gene deletions in Mycobacterium smegmatis.

Project description:Research on mycobacterial genetics relies heavily on techniques for directed gene mutation, but genetic studies are often hampered by the difficulty of generating gene deletions in mycobacteria. We developed an efficient and improved deletion system, described here in detail, which can be used to construct multiple unmarked recombinants in mycobacteria. We tested this system by using it to sequentially delete four pairs of toxin-antitoxin genes in Mycobacterium smegmatis.

| S-EPMC4789726 | biostudies-literature

Exponential-phase glycogen recycling is essential for growth of Mycobacterium smegmatis.

Project description:Bacterial glycogen is a polyglucose storage compound that is thought to prolong viability during stationary phase. However, a specific role for glycogen has not been determined. We have characterized SMEG53, a temperature-sensitive mutant of Mycobacterium smegmatis that contains a mutation in glgE, encoding a putative glucanase. This mutation causes exponentially growing SMEG53 cells to stop growing at 42 degrees C in response to high levels of glycogen accumulation. The mutation in glgE is also associated with an altered growth rate and colony morphology at permissive temperatures; the severity of these phenotypes correlates with the amount of glycogen accumulated by the mutant. Suppression of the temperature-sensitive phenotype, via a decrease in glycogen accumulation, is mediated by growth in certain media or multicopy expression of garA. The function of GarA is unknown, but the presence of a forkhead-associated domain suggests that this protein is a member of a serine-threonine kinase signal transduction pathway. Our results suggest that in M. smegmatis glycogen is continuously synthesized and then degraded by GlgE throughout exponential growth. In turn, this constant recycling of glycogen controls the downstream availability of carbon and energy. Thus, in addition to its conventional storage role, glycogen may also serve as a carbon capacitor for glycolysis during the exponential growth of M. smegmatis.

| S-EPMC94131 | biostudies-literature

Ectoine biosynthesis in Mycobacterium smegmatis.

Project description:Mycobacterium smegmatis is a commonly used mycobacterial model system. Here, we show that M. smegmatis protects itself against elevated salinity by synthesizing ectoine and hydroxyectoine and characterize the phenotype of a nonproducing mutant. This is the first analysis of M. smegmatis halotolerance and of the molecular mechanism that supports it.

| S-EPMC3457100 | biostudies-literature

Transcriptome Landscape of Mycobacterium smegmatis.

Project description:The non-pathogenic bacterium Mycobacterium smegmatis mc2155 has been widely used as a model organism in mycobacterial research, yet a detailed study about its transcription landscape remains to be established. Here we report the transcriptome, expression profiles and transcriptional structures through growth-phase-dependent RNA sequencing (RNA-seq) as well as other related experiments. We found: (1) 2,139 transcriptional start sites (TSSs) in the genome-wide scale, of which eight samples were randomly selected and further verified by 5'-RACE; (2) 2,233 independent monocistronic or polycistronic mRNAs in the transcriptome within the operon/sub-operon structures which are classified into five groups; (3) 47.50% (1016/2139) genes were transcribed into leaderless mRNAs, with the TSSs of 41.3% (883/2139) mRNAs overlapping with the first base of the annotated start codon. Initial amino acids of MSMEG_4921 and MSMEG_6422 proteins were identified by Edman degradation, indicating the presence of distinctive widespread leaderless features in M. smegmatis mc2155. (4) 150 genes with potentially wrong structural annotation, of which 124 proposed genes have been corrected; (5) eight highly active promoters, with their activities further determined by β-galactosidase assays. These data integrated the transcriptional landscape to genome information of model organism mc2155 and lay a solid foundation for further works in Mycobacterium.

| S-EPMC5741613 | biostudies-literature

Methylation of GPLs in Mycobacterium smegmatis and Mycobacterium avium.

Project description:Several species of mycobacteria express abundant glycopeptidolipids (GPLs) on the surfaces of their cells. The GPLs are glycolipids that contain modified sugars including acetylated 6-deoxy-talose and methylated rhamnose. Four methyltransferases have been implicated in the synthesis of the GPLs of Mycobacterium smegmatis and Mycobacterium avium. A rhamnosyl 3-O-methytransferase and a fatty acid methyltransferase of M. smegmatis have been previously characterized. In this paper, we characterize the methyltransferases that are responsible for modifying the hydroxyl groups at positions 2 and 4 of rhamnose and propose the biosynthetic sequence of GPL trimethylrhamnose formation. The analysis of M. avium genes through the creation of specific mutants is technically difficult; therefore, an alternative approach to determine the function of putative methyltransferases of M. avium was undertaken. Complementation of M. smegmatis methyltransferase mutants with M. avium genes revealed that MtfC and MtfB of the latter species have 4-O-methyltransferase activity and that MtfD is a 3-O-methyltransferase which can modify rhamnose of GPLs in M. smegmatis.

| S-EPMC522212 | biostudies-literature

Mycobacterium smegmatis infection of the hand.

Project description:We report a case of Mycobacterium smegmatis granuloma in the soft tissues of the first web space of the left hand in a 67-year-old Caucasian woman. She was in good systematic health; there was no recollection of trauma to the hand. A combined regime of prolonged antibiotic therapy and surgical debridement was necessary to ultimately eradicate the infection. The natural history, microbiology, and treatment of this rare hand infection are discussed.

| S-EPMC2686788 | biostudies-other

Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant.

Project description:Lipoarabinomannans (LAMs) and phosphatidylinositol mannosides (PIMs) are abundant glycolipids in the cell walls of all corynebacteria and mycobacteria, including the devastating human pathogen Mycobacterium tuberculosis. We have recently shown that M. smegmatis mutants of the lipoprotein-encoding lpqW gene have a profound defect in LAM biosynthesis. When these mutants are cultured in complex medium, spontaneous bypass mutants consistently evolve in which LAM biosynthesis is restored at the expense of polar PIM synthesis. Here we show that restoration of LAM biosynthesis in the lpqW mutant results from secondary mutations in the pimE gene. PimE is a mannosyltransferase involved in converting AcPIM4, a proposed branch point intermediate in the PIM and LAM biosynthetic pathways, to more polar PIMs. Mutations in pimE arose due to insertion of the mobile genetic element ISMsm1 and independent point mutations that were clustered in predicted extracytoplasmic loops of this polytopic membrane protein. Our findings provide the first strong evidence that LpqW is required to channel intermediates such as AcPIM4 into LAM synthesis and that loss of PimE function results in the accumulation of AcPIM4, bypassing the need for LpqW. These data highlight new mechanisms regulating the biosynthetic pathways of these essential cell wall components.

| S-EPMC2395014 | biostudies-literature