Disruption of response regulator gene,devR, leads to attenuation in virulence ofMycobacterium tuberculosis

Abstract

The devR-devS two-component system of Mycobacterium tuberculosis was identified earlier and partially characterized in our laboratory. A devR: :kan mutant of M. tuberculosis was constructed by allelic exchange. The devR mutant strain showed reduced cell-tocell adherence in comparison to the parental strain in laboratory culture media. This phenotype was reversed on complementation with a wild-type copy of devR. The devR mutant and parental strains grew at equivalent rates within human monocytes either in the absence or in the presence of lymphocytic cells. The expression of DevR was not modulated upon entry of M. tuberculosis into human monocytes. However, guinea pigs infected with the mutant strain showed a significant decrease in gross lesions in lung, liver and spleen ; only mild pathological changes in liver and lung; and a nearly 3 log lower bacterial burden in spleen compared to guinea pigs infected with the parental strain. Our results suggest that DevR is required for virulence in guinea pigs but is not essential for entry, survival and multiplication of M. tuberculosis within human monocytes in vitro. The attenuation in virulence of the devR mutant in guinea pigs together with DevR-DevS being a bona fide signal transduction system indicates that DevR plays a critical and regulatory role in the adaptation and survival of M. tuberculosis within tissues.

Two Sensor Kinases Contribute to the Hypoxic Response of Mycobacterium tuberculosis

“…In a recent study, a ⌬dosR mutant of MTB was reported to be hypervirulent in both severe combined immunodeficient and DBA mice (29). In contrast, another recent report indicated that a ⌬dosR mutant of MTB was attenuated for virulence in guinea pigs (30). Thus, although both studies implicate the An electrophoretic mobility shift assay was performed using purified DosR or DosR (D54E) and a DNA probe containing a DosR binding motif in the presence or absence of the phosphate donor acetyl phosphate (Acetyl-P).…”

Mycobacterium tuberculosis DosS is a redox sensor and DosT is a hypoxia sensor

“…For example, Mtb responses to NO and hypoxia were shown to be mediated by DosR/S/T and each induced the same transcription profiles (3)(4)(5). Also, Mtb dosR was shown to be essential for full virulence in guinea pigs (23), and iNOS knockout mice were demonstrated to be susceptible to Mtb infection (6). Finally, human Mtbinfected lungs were shown to produce active iNOS (7).…”

High-Throughput Microplate Phosphorylation Assays Based on DevR-DevS/Rv2027c 2-Component Signal Transduction Pathway to Screen for Novel Antitubercular Compounds

“…10,11,17 There is an inherent difficulty in using a coupled assay in a filter-based format owing to an inability to discriminate between the phosphorylated species of the histidine kinase and response regulator. Inhibitors of 2-component systems that inhibited the activity of AlgR1 and AlgR2 proteins regulating alginate biosynthesis in Pseudomonas aeruginosa were discovered using an algD-xylE reporter assay.…”

“…17 However, a devR knockout strain was reported by another laboratory to be hypervirulent in mice. 18 The contradictory findings in the mouse infection model 18 could be due to inherent differences in the 2 mutant strains, in the experimental models and the route of infection used (discussed in Malhotra et al 17 ). For these reasons, DevR is considered to be a crucial regulator of the dormancy response of M. tuberculosis.…”