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Yano K, Masuda K, Akanuma G, Wada T, Matsumoto T, Shiwa Y, Ishige T, Yoshikawa H, Niki H, Inaoka T, Kawamura F. Growth and sporulation defects in Bacillus subtilis mutants with a single rrn operon can be suppressed by amplification of the rrn operon. Microbiology (Reading) 2016; 162:35-45. [DOI: 10.1099/mic.0.000207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Koichi Yano
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan
| | - Kenta Masuda
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan
| | - Genki Akanuma
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan
| | - Tetsuya Wada
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan
| | - Takashi Matsumoto
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Yuh Shiwa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Taichiro Ishige
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Hirofumi Yoshikawa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
- Department of Bioscience, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Hironori Niki
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, Graduate University for Advanced Studies, Sokendai, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Takashi Inaoka
- Microbial Function Laboratory, National Food Research Institute, National Agriculture Research Organization, Tsukuba-shi Kannondai 2-1-12, Ibaraki 305-8642, Japan
| | - Fujio Kawamura
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan
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Abstract
Changes in gene copy number are among the most frequent mutational events in all genomes and were among the mutations for which a physical basis was first known. Yet mechanisms of gene duplication remain uncertain because formation rates are difficult to measure and mechanisms may vary with position in a genome. Duplications are compared here to deletions, which seem formally similar but can arise at very different rates by distinct mechanisms. Methods of assessing duplication rates and dependencies are described with several proposed formation mechanisms. Emphasis is placed on duplications formed in extensively studied experimental situations. Duplications studied in microbes are compared with those observed in metazoan cells, specifically those in genomes of cancer cells. Duplications, and especially their derived amplifications, are suggested to form by multistep processes often under positive selection for increased copy number.
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Affiliation(s)
- Andrew B Reams
- Department of Biological Sciences, California State University, Sacramento, California 95819-6077
| | - John R Roth
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
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The rcbA gene product reduces spontaneous and induced chromosome breaks in Escherichia coli. J Bacteriol 2012; 194:2152-64. [PMID: 22343303 DOI: 10.1128/jb.06390-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Elevated levels of DnaA cause excessive initiation, which leads to an increased level of double-strand breaks that are proposed to arise when newly formed replication forks collide from behind with stalled or collapsed forks. These double-strand breaks are toxic in mutants that are unable to repair them. Using a multicopy suppressor assay to identify genes that suppress this toxicity, we isolated a plasmid carrying a gene whose function had been unknown. This gene, carried by the cryptic rac prophage, has been named rcbA for its ability to reduce the frequency of chromosome breaks. Our study shows that the colony formation of strains bearing mutations in rep, recG, and rcbA, like recA and recB mutants, is inhibited by an oversupply of DnaA and that a multicopy plasmid carrying rcbA neutralizes this inhibition. These and other results suggest that rcbA helps to maintain the integrity of the bacterial chromosome by lowering the steady-state level of double-strand breaks.
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