A mutation in the promoter region of zipA, a component of the divisome, suppresses the shape defect of RodZ-deficient cells

Authors

  • Daisuke Shiomi,

    1. Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan
    Current affiliation:
    1. Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
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  • Hironori Niki

    Corresponding author
    1. Department of Genetics, The Graduate University for Advanced Studies, Mishima, Shizuoka, Japan
    • Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan
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Correspondence

Hironori Niki, Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan. Tel: +81 55 981 6870; Fax: +81 55 981 6826; E-mail: hniki@nig.ac.jp

Abstract

RodZ is important for maintaining the rod shape of Escherichia coli. Loss of RodZ causes conversion of the rod shape to a round shape and a growth rate slower than that of wild-type cells. Suppressor mutations that simultaneously restore both the growth rates and the rod shape were isolated. Most of the suppressor mutations are found in mreB, mrdA, or mrdB. One of the mutations was in the promoter region of zipA, which encodes a crucial component of the cell division machinery. In this study, we investigated the mechanism of the suppression by this mutation. ZipA was slightly but significantly increased in the suppressor cells and led to a delay in cell division. While round-shaped mreB and mrdA mutants lose cell bipolarity, we found that round-shaped rodZ mutants retained cell bipolarity. Therefore, we concluded that a delay in the completion of septation provides extra time to elongate the cell laterally so that the zipA suppressor mutant is able to recover its ovoid or rod shape. The suppression by zipA demonstrates that the regulation of timing of septation potentially contributes to the conversion of morphology in bacterial cells.

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