Six GTP-binding proteins of the Era/Obg family are essential for cell growth in Bacillus subtilis

• Published in: Microbiology (Society for General Microbiology) 2002-11, Vol.148 (11), p.3539-3552
• Main Authors: Morimoto, Takuya, Loh, Pek Chin, Hirai, Tomohiro, Asai, Kei, Kobayashi, Kazuo, Moriya, Shigeki, Ogasawara, Naotake
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacillus subtilis; Bacillus subtilis - growth & development; Bacillus subtilis - physiology; Bacterial Proteins - chemistry; Bacterial Proteins - classification; Bacteriology; Biological and medical sciences; Chromosomes, Bacterial - physiology; Era protein; Escherichia coli; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Growth, nutrition, cell differenciation; GTP-binding protein; GTP-Binding Proteins - chemistry; GTP-Binding Proteins - classification; GTP-Binding Proteins - physiology; Guanosine Diphosphate - metabolism; Guanosine Triphosphate - metabolism; Microbiology; Molecular Sequence Data; Obg protein; Phylogeny; RNA-Binding Proteins; Sequence Homology, Amino Acid
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-148-11-3539

Department of Microbial Cell Biology, Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan 1 Author for correspondence: Naotake Ogasawara. Tel: [phone]. Fax: [phone]. e-mail: nogasawa{at}bs.aist-nara.ac.jp GTP-binding proteins are found in all domains of life and are involved in various essential cellular processes. With the recent explosion of available genome sequence data, a widely distributed bacterial subfamily of GTP-binding proteins was discovered, represented by the Escherichia coli Era and the Bacillus subtilis Obg proteins. Although only a limited number of theGTP-binding proteins belonging to the subfamily have been experimentally characterized, and their function remains unknown, the available data suggests that many of them are essential to bacterial growth. When the complete genomic sequence of B. subtilis was surveyed for genes encoding GTP-binding proteins of the Era/Obg family, nine such genes were identified. As a first step in elucidating the functional networks of those nine GTP-binding proteins, data presented here indicates that six of them are essential for B. subtilis viability. Additionally, it is shown that the six essential proteins are able to specifically bind GTP and GDP in vitro . Experimental depletion of the essential GTP-binding proteins was examined in the context of cell morphology and chromosome replication, and it was found that two proteins, Bex and YqeH, appeared to participate in the regulation of initiation of chromosome replication. Collectively, these results suggest that members of the GTP-binding Era/Obg family are important proteins with precise, yet still not fully understood, roles in bacterial growth and viability. Keywords: bacterial GTPase, molecular switch protein, bacterial growth, regulation of initiation of chromosome replication b The primer sequences used for PCR in this study are shown as supplementary data on Microbiology Online (http://mic.sgmjournals.org). a Present address: Faculty of Science, Saitama University, 255 Ohkubo, Saitama, Saitama 338-8570, Japan.