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

20 View
0 Download
1 Citations

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

15 View
0 Download
11 Citations

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.

Research Support, Non-U.S. Gov'ts

Crystal structure and modeling of the tetrahedral intermediate state of methylmalonate-semialdehyde dehydrogenase (MMSDH) from Oceanimonas doudoroffii: Hackwon Do , Chang Woo Lee , Sung Gu Lee , Hara Kang , Chul Min Park , Hak Jun Kim , Hyun Park , HaJeung Park , Jun Hyuck Lee; J. Microbiol. 2016;54(2):114-121. Published online February 2, 2016; DOI: https://doi.org/10.1007/s12275-016-5549-2

11 View
0 Download
6 Citations

Abstract: The gene product of dddC (Uniprot code G5CZI2), from the Gram-negative marine bacterium Oceanimonas doudoroffii, is a methylmalonate-semialdehyde dehydrogenase (OdoMMSDH) enzyme. MMSDH is a member of the aldehyde dehydrogenase superfamily, and it catalyzes the NADdependent decarboxylation of methylmalonate semialdehyde to propionyl-CoA. We determined the crystal structure of OdoMMSDH at 2.9 Å resolution. Among the twelve molecules in the asymmetric unit, six subunits complexed with NAD, which was carried along the protein purification steps. OdoMMSDH exists as a stable homodimer in solution; each subunit consists of three distinct domains: an NAD-binding domain, a catalytic domain, and an oligomerization domain. Computational modeling studies of the OdoMMSDH structure revealed key residues important for substrate recognition and tetrahedral intermediate stabilization. Two basic residues (Arg103 and Arg279) and six hydrophobic residues (Phe150, Met153, Val154, Trp157, Met281, and Phe449) were found to be important for tetrahedral intermediate binding. Modeling data also suggested that the backbone amide of Cys280 and the side chain amine of Asn149 function as the oxyanion hole during the enzymatic reaction. Our results provide useful insights into the substrate recognition site residues and catalytic mechanism of OdoMMSDH.

Inactivation of Barotolerant Strains of Listeria monocytogenes and Escherichia coli O157:H7 by Ultra High Pressure and tert-Butylhydroquinone Combination: Yoon-Kyung Chung , Ahmed E. Yousef; J. Microbiol. 2008;46(3):289-294. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-008-0090-6

14 View
0 Download
8 Citations

Abstract: Antimicrobial efficacy of ultra-high-pressure (UHP) can be enhanced by application of additional hurdles. The objective of this study was to systematically assess the enhancement in pressure lethality by TBHQ treatment, against barotolerant strains of Escherichia coli O157:H7 and Listeria monocytogenes. Two L. monocytogenes Scott A and the barotolerant OSY-328 strain, and two E. coli O157:H7 strains, EDL-933 and its barotolerant mutant, OSY-ASM, were tested. Cell suspensions containing TBHQ (50 ppm, dissolved in dimethyl sulfoxide) were pressurized at 200 to 500 MPa (23±2°C) for 1 min, plated on tryptose agar and enumerated the survivors. The TBHQ-UHP combination resulted in synergistic inactivation of both pathogens, with different degrees of lethality among strains. The pressure lethality threshold, for the combination treatment, was lower for E. coli O157:H7 (≥ 200 MPa) than for L. monocytogenes (> 300 MPa). E. coli O157:H7 strains were extremely sensitive to the TBHQ-UHP treatment, compared to Listeria strains. Interestingly, a control treatment involving DMSO-UHP combination consistently resulted in higher inactivation than that achieved by UHP alone, against all strains tested. However, sensitization of the pathogens to UHP by the additives (TBHQ in DMSO) was prominently greater for UHP than DMSO. Differences in sensitivities to the treatment between these two pathogens may be attributed to discrepancies in cellular structure or physiological functions.

Identification of Medicinal Mushroom Species Based on Nuclear Large Subunit rDNA Sequences: Ji Seon Lee , Mi Ok Lim , Kyoung Yeh Cho , Jung Hee Cho , Seung Yeup Chang , Doo Hyun Nam; J. Microbiol. 2006;44(1):29-34.; DOI: https://doi.org/2340 [pii]

11 View
0 Download

Abstract: The purpose of this study was to develop molecular identification method for medical mushrooms and their preparations based on the nucleotide sequences of nuclear large subunit (LSU) rDNA. Four specimens were collected of each of the three representative medicinal mushrooms used in Korea: Ganoderma lucidum, Coriolus versicolor, and Fomes fomentarius. Fungal material used in these experiments included two different mycelial cultures and two different fruiting bodies from wild or cultivated mushrooms. The genomic DNA of mushrooms were extracted and 3 nuclear LSU rDNA fragments were amplified: set 1 for the 1.1-kb DNA fragment in the upstream region, set 2 for the 1.2-kb fragment in the middle, and set 3 for the 1.3-kb fragment downstream. The amplified gene products of nuclear large subunit rDNA from 3 different mushrooms were cloned into E. coli vector and subjected to nucleotide sequence determination. The sequence thus determined revealed that the gene sequences of the same medicinal mushroom species were more than 99.48% homologous, and the consensus sequences of 3 different medicinal mushrooms were more than 97.80% homologous. Restriction analysis revealed no useful restriction sites for 6-bp recognition enzymes for distinguishing the 3 sequences from one another, but some distinctive restriction patterns were recognized by the 4-bp recognition enzymes AccII and HhaI. This analysis was also confirmed by PCR-RFLP experiments on medicinal mushrooms.

First
Prev
Page of 1
Next
Last

Search