Journal of Microbiology

Eunsil Choi

2 Articles

Functional characterization of HigBA toxin-antitoxin system in an Arctic bacterium, Bosea sp. PAMC 26642: Eunsil Choi , Ahhyun Huh , Changmin Oh , Jeong-Il Oh , Ho Young Kang , Jihwan Hwang; J. Microbiol. 2022;60(2):192-206. Published online February 1, 2022; DOI: https://doi.org/10.1007/s12275-022-1619-9

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Toxin-antitoxin (TA) systems are growth-controlling genetic elements consisting of an intracellular toxin protein and its cognate antitoxin. TA systems have been spread among microbial genomes through horizontal gene transfer and are now prevalent in most bacterial and archaeal genomes. Under normal growth conditions, antitoxins tightly counteract the activity of the toxins. Upon stresses, antitoxins are inactivated, releasing activated toxins, which induce growth arrest or cell death. In this study, among nine functional TA modules in Bosea sp. PAMC 26642 living in Arctic lichen, we investigated the functionality of BoHigBA2. BohigBA2 is located close to a genomic island and adjacent to flagellar gene clusters. The expression of BohigB2 induced the inhibition of E. coli growth at 37°C, which was more manifest at 18°C, and this growth defect was reversed when BohigA2 was co-expressed, suggesting that this BoHigBA2 module might be an active TA module in Bosea sp. PAMC 26642. Live/dead staining and viable count analyses revealed that the BoHigB2 toxin had a bactericidal effect, causing cell death. Furthermore, we demonstrated that BoHigB2 possessed mRNA-specific ribonuclease activity on various mRNAs and cleaved only mRNAs being translated, which might impede overall translation and consequently lead to cell death. Our study provides the insight to understand the cold adaptation of Bosea sp. PAMC 26642 living in the Arctic.

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Evaluating the Contribution of the Predicted Toxin–Antitoxin System HigBA to Persistence, Biofilm Formation, and Virulence in Burkholderia pseudomallei
Itziar Chapartegui-González, Nittaya Khakhum, Jacob L. Stockton, Alfredo G. Torres, Igor E. Brodsky
Infection and Immunity.2022;[Epub] CrossRef
Chronicle of Research into Lichen-Associated Bacteria
Zichen He, Takeshi Naganuma
Microorganisms.2022; 10(11): 2111. CrossRef
Degradation of amoxicillin by newly isolated Bosea sp. Ads-6
Lei Yan, Ning Yan, Xi-Yan Gao, Ying Liu, Zhi-Pei Liu
Science of The Total Environment.2022; 828: 154411. CrossRef

Functional and structural characterization of Deinococcus radiodurans R1 MazEF toxin-antitoxin system, Dr0416-Dr0417: Immanuel Dhanasingh , Eunsil Choi , Jeongeun Lee , Sung Haeng Lee , Jihwan Hwang; J. Microbiol. 2021;59(2):186-201. Published online February 1, 2021; DOI: https://doi.org/10.1007/s12275-021-0523-z

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Abstract PDF

In prokaryotes, toxin-antitoxin (TA) systems are commonly found. They likely reflect the adaptation of pathogenic bacteria or extremophiles to various unfavorable environments by slowing their growth rate. Genomic analysis of the extremophile Deinococcus radiodurans R1 revealed the presence of eight type II TA systems, including the genes dr0417, dr0660, dr1530, dr0690, and dr1807. Expression of these toxin genes led to inhibition of Escherichia coli growth, whereas their antidote antitoxins were able to recover the growth defect. Remarkably, Dr0417 (DrMazF) showed endoribonuclease activity toward rRNAs as well as mRNAs, as determined by in vivo and in vitro RNA cleavage assays, and this activity was inhibited by Dr0416 (DrMazE). It was also found that the expression of dr0416-0417 module is directly regulated by the DrMazE-MazF complex. Furthermore, this TA module was induced under stress conditions and plays an important role in survival. To understand the regulatory mechanism at the molecular level, we determined the first high-resolution structures of DrMazF alone and of the DrMazE-MazF complex. In contrast with the hetero-hexameric state of typical MazEMazF complexes found in other species, DrMazE-MazF crystal structure consists of a hetero-trimer, with the DNA-binding domain of DrMazE undergoing self-cleavage at the flexible linker loop. Our structure revealed that the unique residue R54 provides an additional positive charge to the substratebinding pocket of DrMazF, its mutation significantly affects the endonuclease activity. Thus, our work reports the unique structural and biochemical features of the DrMazE-MazF system.

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Functional characterization of HigBA toxin-antitoxin system in an Arctic bacterium, Bosea sp. PAMC 26642
Eunsil Choi, Ahhyun Huh, Changmin Oh, Jeong-Il Oh, Ho Young Kang, Jihwan Hwang
Journal of Microbiology.2022; 60(2): 192. CrossRef
Identification and characterization of the type II toxin-antitoxin systems in the carbapenem-resistant Acinetobacter baumannii
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Microbial Pathogenesis.2021; 158: 105052. CrossRef

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