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Characterization of an interplay between a Mycobacterium tuberculosis MazF homolog, Rv1495 and its sole DNA topoisomerase I.

ABSTRACT: The MazEF systems are thought to contribute to the capacity for long-term dormancy observed in the human pathogen, Mycobacterium tuberculosis. However, except for their functions as mRNA interferases, little is known regarding any additional cellular functions of these systems in the pathogen. In the present study, we observed a negative interplay between MazF protein Rv1495 and the sole M. tuberculosis DNA topoisomerase I (MtbTopA) with respect to protein functions. Through its C-terminal domain, MtbTopA physically interacted with and inhibited the mRNA cleavage activity of Rv1495. Rv1495, in turn, inhibited the DNA cleavage activity of MtbTopA as well as its function of relaxation of supercoiled DNA. An N-terminus fragment of Rv1495, designated Rv1495-N(29-56), lost mRNA cleavage activity, but retained a significant physical interaction and inhibitory effect on TopA proteins from both M. tuberculosis and M. smegmatis. This fragment, although less effective than the full-length protein, was able to inhibit mycobacterial growth when expressed through a recombinant plasmid in M. smegmatis. The Rv1495 physically interacted with the M. smegmatis TopA both in vitro and in vivo. Our findings imply that MazEF systems can affect bacterial survival by a novel mechanism that allows direct modulation of M. tuberculosis topoisomerase I.

SUBMITTER: Huang F

PROVIDER: S-EPMC3001090 | biostudies-other | 2010 Dec

REPOSITORIES: biostudies-other

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Characterization of an interplay between a Mycobacterium tuberculosis MazF homolog, Rv1495 and its sole DNA topoisomerase I.

Huang Feng F He Zheng-Guo ZG

Nucleic acids research 20100819 22

The MazEF systems are thought to contribute to the capacity for long-term dormancy observed in the human pathogen, Mycobacterium tuberculosis. However, except for their functions as mRNA interferases, little is known regarding any additional cellular functions of these systems in the pathogen. In the present study, we observed a negative interplay between MazF protein Rv1495 and the sole M. tuberculosis DNA topoisomerase I (MtbTopA) with respect to protein functions. Through its C-terminal domai ...[more]

PMID: 20724443

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Project description:Numerous studies show efflux as a universal bacterial mechanism contributing to antibiotic resistance and also that the activity of the antibiotics subject to efflux can be enhanced by the combined use of efflux inhibitors. Nevertheless, the contribution of efflux to the overall drug resistance levels of clinical isolates of Mycobacterium tuberculosis is poorly understood and still is ignored by many. Here, we evaluated the contribution of drug efflux plus target-gene mutations to the drug resistance levels in clinical isolates of M. tuberculosis. A panel of 17 M. tuberculosis clinical strains were characterized for drug resistance associated mutations and antibiotic profiles in the presence and absence of efflux inhibitors. The correlation between the effect of the efflux inhibitors and the resistance levels was assessed by quantitative drug susceptibility testing. The bacterial growth/survival vs. growth inhibition was analyzed through the comparison between the time of growth in the presence and absence of an inhibitor. For the same mutation conferring antibiotic resistance, different MICs were observed and the different resistance levels found could be reduced by efflux inhibitors. Although susceptibility was not restored, the results demonstrate the existence of a broad-spectrum synergistic interaction between antibiotics and efflux inhibitors. The existence of efflux activity was confirmed by real-time fluorometry. Moreover, the efflux pump genes mmr, mmpL7, Rv1258c, p55, and efpA were shown to be overexpressed in the presence of antibiotics, demonstrating the contribution of these efflux pumps to the overall resistance phenotype of the M. tuberculosis clinical isolates studied, independently of the genotype of the strains. These results showed that the drug resistance levels of multi- and extensively-drug resistant M. tuberculosis clinical strains are a combination between drug efflux and the presence of target-gene mutations, a reality that is often disregarded by the tuberculosis specialists in favor of the almost undisputed importance of antibiotic target-gene mutations for the resistance in M. tuberculosis.

Project description:Tuberculosis (TB), caused by the human pathogens Mycobacterium tuberculosis (Mtb) and Mycobacterium africanum, has plagued humanity for millennia and remains the deadliest infectious disease in the modern world. Mycobacterium tuberculosis and M. africanum can be subdivided phylogenetically into seven lineages exhibiting a low but significant degree of genomic diversity and preferential geographic distributions. Human genetic variability impacts all stages of TB pathogenesis ranging from susceptibility to infection with Mtb, progression of infection to disease, and the development of distinct clinical subtypes. The genetic study of severe childhood TB identified strong inborn single-gene errors revealing crucial pathways of vulnerability to TB. However, the identification of major TB-susceptibility genes on the population level has remained elusive. In particular, the replication of findings from candidate and genome-wide association studies across distinct human populations has proven difficult, thus hampering the characterization of reliable host molecular markers of susceptibility. Among the possible confounding factors of genetic association studies is Mtb genomic variability, which generally was not taken into account by human genetic studies. In support of this possibility, Mtb lineage was found to be a contributing factor to clinical presentation of TB and epidemiological spread of Mtb in exposed populations. The confluence of pathogen and human host genetic variability to TB pathogenesis led to the consideration of a possible coadaptation of Mtb strains and their human hosts, which should reveal itself in significant interaction effects between Mtb strain and TB-susceptibility/resistance alleles. Here, we present some of the most consistent findings of genetic susceptibility factors in human TB and review studies that point to genome-to-genome interaction between humans and Mtb lineages. The limited results available so far suggest that analyses considering joint human-Mtb genomic variability may provide improved power for the discovery of pathogenic drivers of the ongoing TB epidemic.

Dataset Information

Characterization of an interplay between a Mycobacterium tuberculosis MazF homolog, Rv1495 and its sole DNA topoisomerase I.

Publications

Characterization of an interplay between a Mycobacterium tuberculosis MazF homolog, Rv1495 and its sole DNA topoisomerase I.

Similar Datasets

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