著者

Yu Shinjyo Naoya Midorikawa Takashi Matsumoto Yuki Sugaya Yoshiki Ozawa Ayumi Oana Chiaki Horie Hirofumi Yoshikawa Yasuhiro Takahashi Toshio Hasegawa Kei Asai

出版者

Applied Microbiology, Molecular and Cellular Biosciences Research Foundation

雑誌

The Journal of General and Applied Microbiology (ISSN:00221260)

巻号頁・発行日

vol.68, no.2, pp.62-70, 2022 (Released:2022-09-15)

参考文献数

62

被引用文献数

1

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Recently, the antibacterial effects of essential oils have been investigated in addition to their therapeutic purposes. Owing to their hydrophobic nature, they are thought to perturb the integrity of the bacterial cell membrane, leading to cell death. Against such antibiotic challenges, bacteria develop mechanisms for cell envelope stress responses (CESR). In Bacillus subtilis, a gram-positive sporulating soil bacterium, the extracytoplasmic function (ECF) sigma factor-mediated response system plays a pivotal role in CESR. Among them, σM is strongly involved in response to cell envelope stress, including a shortage of available bactoprenol. Vetiver essential oil, a product of Chrysopogon zizanioides (L.) Roberty root, is also known to possess bactericidal activity. σM was exclusively and strongly induced when the cells were exposed to Vetiver extract, and depletion of multi-ECF sigma factors (ΔsigM, ΔsigW, ΔsigX, and ΔsigV) enhanced sensitivity to it. From this quadruple mutant strain, the suppressor strains, which restored resistance to the bactericidal activity of Vetiver extract, emerged, although attempts to obtain resistant strains from the wild type did not succeed. Whole-genome resequencing of the suppressor strains and genetic analysis revealed inactivation of xseB or pnpA, which code for exodeoxyribonuclease or polynucleotide phosphorylase, respectively. This allowed the quadruple mutant strain to escape from cell death caused by Vetiver extract. Composition analysis suggested that the sesquiterpene, khusimol, might contribute to the bactericidal activity of the Vetiver extract.

著者

Masakazu Saito Satoru Watanabe Kaori Nimura-Matsune Hirofumi Yoshikawa Hitoshi Nakamoto

出版者

Applied Microbiology, Molecular and Cellular Biosciences Research Foundation

雑誌

The Journal of General and Applied Microbiology (ISSN:00221260)

巻号頁・発行日

pp.2020.02.001, (Released:2020-04-10)

参考文献数

29

被引用文献数

1

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The CIRCE/HrcA system is highly conserved in cyanobacterial genomes. We have shown that heat-shock induction of the groESL1 operon in the cyanobacterium Synechocystis sp. PCC6803 is negatively regulated by the CIRCE/HrcA system. In Synechococcus elongatus PCC7942, a novel heat shock protein, Orf7.5, is involved in positive regulation of the groESL1 transcription. However, Orf7.5 is not conserved in some cyanobacteria, including Synechocystis sp. PCC6803. The purpose of this study is to evaluate the functional conservation of the CIRCE/HrcA system in S. elongatus PCC7942 and to understand the interplay between the CIRCE/HrcA system and the Orf7.5 regulatory system. We constructed single and double mutants of S. elongatus orf7.5, hrcA and orf7.5/hrcA and heat induction of the groESL1 transcription in these mutants was analyzed. Unexpectedly, derepression of the groESL1 transcription in an hrcA mutant was not observed. In all these mutants, the transcription was greatly suppressed under both normal and heat stress conditions, indicating that both HrcA and Orf7.5 are involved in regulation of the groESL1 transcription in a positive way. Consistent with the decrease in the groESL1 mRNA level, all the single and double mutants showed a great loss of acquired thermotolerance. Heat induction of the orf7.5 promoter activity was totally diminished in the orf7.5 mutant, indicating that Orf7.5 activates its own transcription. Yeast two hybrid analysis showed that the principle sigma factor RpoD1 interacts with Orf7.5. These results indicate that Orf7.5 enhances the transcription of groESL1 and orf7.5 by interacting with RpoD1.

著者

Motohiro Akashi Shota Harada Syunsuke Moki Yuki Okouji Kiwamu Takahashi Shigeki Kada Keigo Yamagami Yasuhiko Sekine Satoru Watanabe Taku Chibazakura Hirofumi Yoshikawa

出版者

日本遺伝学会

雑誌

Genes & Genetic Systems (ISSN:13417568)

巻号頁・発行日

pp.16-00071, (Released:2017-03-24)

被引用文献数

3

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We developed an insertion sequence transposition detection system called the "jumping cat assay" and applied it to the Bacillus subtilis chromosome using IS256Bsu1 derived from B. subtilis natto. The high frequency of transposition enabled us to explore host factors; combining the assay and genetic analyses revealed that recA is essential for the transposition of IS256Bsu1. Detailed analyses using various domain mutants of recA demonstrated that this essentiality is not related to the function of recA in homologous recombination. Instead, the ATP binding and hydrolysis function seemed to be crucial for IS transposition. To elucidate the role of recA, we focused on the muB gene of the enterobacteriophage Mu. Based on information from the NCBI Conserved Domain Database, both MuB and RecA belong to the P-loop dNTPase superfamily. Further experiments revealed that muB complements the transposition-defective phenotype of a recA deletant, although it could not rescue UV sensitivity. These results suggest that recA shares a common function with muB that helps the transposition of IS256Bsu1 in B. subtilis.

著者

Ryudo Ohbayashi Hideto Akai Hirofumi Yoshikawa Wolfgang R. Hess Satoru Watanabe

出版者

公益財団法人 応用微生物学・分子細胞生物学研究奨励会

雑誌

The Journal of General and Applied Microbiology (ISSN:00221260)

巻号頁・発行日

pp.2016.02.002, (Released:2016-06-01)

参考文献数

32

被引用文献数

43

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Cyanobacteria are photosynthetic microorganisms that serve as experimental model organisms for the study of photosynthesis, environmental stress responses, and the production of biofuels. Genetic tools for bioengineering have been developed as a result of such studies. However, there is still room for improvement for the tight control of experimental protein expression in these microorganisms. Here, we describe an expression system controlled by a theophylline-responsive riboswitch that we have constructed in the cyanobacterium Synechocystis sp. PCC 6803. We demonstrate that, in response to different theophylline concentrations, this riboswitch can tightly control green fluorescence protein expression in Synechocystis. Thus, this system is useful as a tool for genetic engineering and the synthetic biology of cyanobacteria.