|専攻分野||Plant molecular and cellular biology|
1.Kojima S, Muramoto K, Kusano T (2016) Outer membrane proteins derived from non-cyanobacterial lineage cover the peptidoglycan of Cyanophora paradoxa cyanelles and serve as a cyanelle diffusion channel. J. Biol. Chem. 291:20198-20209.
2.Sugawara E, Kojima S, Nikaido H (2016) Klebsiella pneumoniae major porins OmpK35 and OmpK36 allow more efficient diffusion of β-lactams than their Escherichia coli homologs OmpF and OmpC. J. Bacteriol. DOI:10.1128/JB.00590-16
3.Kojima S, Hayashi K, Tochigi S, Kusano T, Kaneko J, Kamio Y (2016) Peptidoglycan-associated outer membrane protein Mep45 of rumen anaerobe Selenomonas ruminantium forms a non-specific diffusion pore via its C-terminal transmembrane domain. Biosci. Biotech. Biochem. 80:1954-1959.
4.Kowata H, Tochigi S, Kusano T, Kojima S (2016) Quantitative measurement of the outer membrane permeability in Escherichia coli lpp and tol-pal mutants defines the significance of Tol-Pal function for maintaining drug resistance. J. Antibiotics. DOI:10.1038/ja.2016.50.
5.Kojima, S, Nikaido H. (2014) High salt concentrations increase permeability through OmpC channels of Escherichia coli. J. Biol. Chem. 289:26464-26473.
6.Kojima S, Nikaido H (2013) Permeation rates of penicillins indicate that Escherichia coli porins function principally as nonspecific channels. Proc. Natl. Acad. Sci. U. S. A. 110(28): E2629-E2634.
7.Kojima S, Kamio Y (2012) Molecular basis for the maintenance of envelope integrity in Selenomonas ruminantium: cadaverine biosynthesis and covalent modification into the peptidoglycan play a major role. J. Nutr. Sci. Vitaminol. (Tokyo) 58(3): 153-160.
8.Kojima S, Kaneko J, Abe N, Takatsuka Y, Kamio Y (2011) Cadaverine covalently linked to the peptidoglycan serves as the correct constituent for the anchoring mechanism between the outer membrane and peptidoglycan in Selenomonas ruminantium. J. Bacteriol. 193(9): 2347-2350.
9.Kojima S, Ko KC, Takatsuka Y, Kaneko J, Itoh Y, Kamio Y. (2010) Cadaverine covalently linked to peptidoglycan is required for interaction between the peptidoglycan and the periplasm-exposed S-layer-homologous domain of major outer membrane protein Mep45 in Selenomonas ruminantium. J. Bacteriol. 192(22): 5953-5961.
|所属学会||Japanese society for Bacteriology
Japan society for Bioscience, Biotechnology, and Agrochemistry
The Botanical Society of Japan
Interior and exterior of living organism is separated by cell envelope. Therefore, the structure and function of the cell envelope are critical for various aspects of cellular activity such as transport, morphogenesis, response to extracellular environment, and so on. I've been interested in the cell surface of Gram-negative bacteria, which comprises cytoplasmic membrane, peptidoglycan (cell wall) layer, and outer membrane. During my Ph. D. study, I examined molecular basis of the interaction between the outer membrane and underlying peptidoglycan layer, an “anchor” crucial for maintaining structural integrity of the outer membrane (Kojima et al. 2010, 2011). As a postdoc, with the aim of understanding quantitatively the function of the outer membrane, I examined the permeability of the outer membrane by analyzing the movement of substances across the outer membrane, using β-lactam antibiotics as substrates (Kojima & Nikaido 2013, 2014).
Because the outer membrane directly affects the speed of flux of various substances to/from the cell, its permeability is quantitatively linked to the cellular physiology, survival and responses to the external environment. My current researches focus on the molecular basis of the permeability and stability of the outer membrane, in the context of nutrient uptake and also the antibiotic resistance of Gram-negative bacteria. Also, I started recently the research on the outer membrane of chloroplasts, an organelle descended from endosymbiotic cyanobacteria (Gram-negative bacteria that conduct oxygenic photosynthesis). The aim of this research is to understand how the function of the outer membrane has changed (or preserved) during the course of evolution from free living cyanobacteria to chloroplasts.
Current projects are: 1) Mechanism of antibiotic resistance of Gram-negative bacteria, 2) Function of the outer membrane of primitive chloroplast, and 3) Outer membrane structure and function of ruminal bacteria.(for detailed information: