Journal of Microbiology

Review

Mycobacterial Regulatory Systems Involved in the Regulation of Gene Expression Under Respiration‑Inhibitory Conditions: Yuna Oh , Ha-Na Lee , Eon-Min Ko , Ji-A Jeong , Sae Woong Park , Jeong-Il Oh; J. Microbiol. 2023;61(3):297-315. Published online February 27, 2023; DOI: https://doi.org/10.1007/s12275-023-00026-8

Abstract: Mycobacterium tuberculosis is the causative agent of tuberculosis. M. tuberculosis can survive in a dormant state within the granuloma, avoiding the host-mounting immune attack. M. tuberculosis bacilli in this state show increased tolerance to antibiotics and stress conditions, and thus the transition of M. tuberculosis to the nonreplicating dormant state acts as an obstacle to tuberculosis treatment. M. tuberculosis in the granuloma encounters hostile environments such as hypoxia, nitric oxide, reactive oxygen species, low pH, and nutrient deprivation, etc., which are expected to inhibit respiration of M. tuberculosis. To adapt to and survive in respiration-inhibitory conditions, it is required for M. tuberculosis to reprogram its metabolism and physiology. In order to get clues to the mechanism underlying the entry of M. tuberculosis to the dormant state, it is important to understand the mycobacterial regulatory systems that are involved in the regulation of gene expression in response to respiration inhibition. In this review, we briefly summarize the information regarding the regulatory systems implicated in upregulation of gene expression in mycobacteria exposed to respiration-inhibitory conditions. The regulatory systems covered in this review encompass the DosSR (DevSR) two-component system, SigF partner switching system, MprBA-SigE-SigB signaling pathway, cAMP receptor protein, and stringent response.

Journal Article

Isolation, cultivation, and genome analysis of proteorhodopsincontaining SAR116-clade strain Candidatus Puniceispirillum marinum IMCC1322: Junhak Lee , Kae Kyoung Kwon , Seung-Il Lim , Jaeho Song , Ah Reum Choi , Sung-Hyun Yang , Kwang-Hwan Jung , Jung-Hyun Lee , Sung Gyun Kang , Hyun-Myung Oh , Jang-Cheon Cho; J. Microbiol. 2019;57(8):676-687. Published online June 14, 2019; DOI: https://doi.org/10.1007/s12275-019-9001-2

Abstract: Strain IMCC1322 was isolated from a surface water sample from the East Sea of Korea. Based on 16S rRNA analysis, IMCC1322 was found to belong to the OCS28 sub-clade of SAR116. The cells appeared as short vibrioids in logarithmicphase culture, and elongated spirals during incubation with mitomycin or in aged culture. Growth characteristics of strain IMCC1322 were further evaluated based on genomic information; proteorhodopsin (PR), carbon monoxide dehydrogenase, and dimethylsulfoniopropionate (DMSP)-utilizing enzymes. IMCC1322 PR was characterized as a functional retinylidene protein that acts as a light-driven proton pump in the cytoplasmic membrane. However, the PR-dependent phototrophic potential of strain IMCC1322 was only observed under CO-inhibited and nutrient-limited culture conditions. A DMSP-enhanced growth response was observed in addition to cultures grown on C1 compounds like methanol, formate, and methane sulfonate. Strain IMCC1322 cultivation analysis revealed biogeochemical processes characteristic of the SAR116 group, a dominant member of the microbial community in euphotic regions of the ocean. The polyphasic taxonomy of strain IMCC1322 is given as Candidatus Puniceispirillum marinum, and was confirmed by chemotaxonomic tests, in addition to 16S rRNA phylogeny and cultivation analyses.

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