Journal of Microbiology

Journal Article

Improved tolerance of Escherichia coli to oxidative stress by expressing putative response regulator homologs from Antarctic bacteria: Seo-jeong Park , Sangyong Lim , Jong-il Choi; J. Microbiol. 2020;58(2):131-141. Published online December 23, 2019; DOI: https://doi.org/10.1007/s12275-020-9290-5

Abstract: Response regulator (RR) is known a protein that mediates cell’s response to environmental changes. The effect of RR from extremophiles was still under investigation. In this study, response regulator homologs were mined from NGS data of Antarctic bacteria and overexpressed in Escherichia coli. Sixteen amino acid sequences were annotated corresponding to response regulators related to the two-component regulatory systems; of these, 3 amino acid sequences (DRH632, DRH1601 and DRH577) with high homology were selected. These genes were cloned in pRadGro and expressed in E. coli. The transformant strains were subjected to various abiotic stresses including oxidative, osmotic, thermal stress, and acidic stress. There was found that the robustness of E. coli to abiotic stress was increased in the presence of these response regulator homologs. Especially, recombinant E. coli overexpressing drh632 had the highest survival rate in oxidative, hypothermic, osmotic, and acidic conditions. Recombinant E. coli overexpressing drh1601 showed the highest tolerance level to osmotic stress. These results will be applicable for development of recombinant strains with high tolerance to abiotic stress.

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

NOTE] Probing the ArcA Regulon in the Rumen Bacterium Mannheimia succiniciproducens by Genome-Wide Expression Profiling: Seulgi Yun , Jong Moon Shin , Oh-Cheol Kim , Young Ryul Jung , Doo-Byoung Oh , Sang Yup Lee , Ohsuk Kwon; J. Microbiol. 2012;50(4):665-672. Published online July 21, 2012; DOI: https://doi.org/10.1007/s12275-012-2007-7

Abstract: In this study, the putative target genes of the Arc two-component system of the rumen bacterium Mannheimia succiniciproducens were determined by analyzing the transcriptome of the ArcA overexpression strain and by the in silico scanning of the entire genome sequence with the position weight matrix of the ArcA binding sequence developed for Escherichia coli. The majority of 79 repressed genes were involved in energy metabolism and carbohydrate transport and metabolism, while the majority of 82 induced genes were involved in hypothetical or unknown functions. Our results suggest that the Arc system in M. succiniciproducens has a specific function that differs from that in E. coli.

Protein-Protein Interactions between Histidine Kinases and Response Regulators of Mycobacterium tuberculosis H37Rv: Ha-Na Lee , Kwang-Eun Jung , In-Jeong Ko , Hyung Suk Baik , Jeong-Il Oh; J. Microbiol. 2012;50(2):270-277. Published online April 27, 2012; DOI: https://doi.org/10.1007/s12275-012-2050-4

Abstract: Using yeast two-hybrid assay, we investigated protein-protein interactions between all orthologous histidine kinase (HK)/response regulator (RR) pairs of M. tuberculosis H37Rv and identified potential protein-protein interactions between a noncognate HK/RR pair, DosT/NarL. The protein interaction between DosT and NarL was verified by phosphotransfer reaction from DosT to NarL. Furthermore, we found that the DosT and DosS HKs, which share considerable sequence similarities to each other and form a twocomponent system with the DosR RR, have different crossinteraction capabilities with NarL: DosT interacted with NarL, while DosS did not. The dimerization domains of DosT and DosS were shown to be sufficient to confer specificity for DosR, and the different cross-interaction abilities of DosS and DosT with NarL were demonstrated to be attributable to variations in the amino acid sequences of the α2-helices of their dimerization domains.

NOTE] Evidence Against the Physiological Role of Acetyl Phosphate in the Phosphorylation of the ArcA Response Regulator in Escherichia coli: Xueqiao Liu , Gabriela R. Peña Sandoval , Barry L. Wanner , Won Seok Jung , Dimitris Georgellis , Ohsuk Kwon; J. Microbiol. 2009;47(5):657-662. Published online October 24, 2009; DOI: https://doi.org/10.1007/s12275-009-0087-9

Abstract: The Arc two-component signal transduction system of Escherichia coli comprises the ArcB sensor kinase and the ArcA response regulator. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which, in turn, represses or activates its target operons. ArcA has been shown to be able to autophosphorylate in vitro at the expense of acetyl-P. Here, the in vivo effect of acetyl phosphate on the redox signal transduction by the Arc system was assessed. Our results indicate that acetyl phosphate can modulate the expression of ArcA-P target genes only in the absence of ArcB. Therefore, the acetyl phosphate dependent ArcA phosphorylation route does not seem to play a significant role under physiological conditions.

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