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Using Coculture to Detect Chemically Mediated Interspecies Interactions
Published on: November 1, 2013
Protein traffic for secretion and related machinery of Bacillus subtilis
Kunio Yamane1, Keigo Bunai, Hiroshi Kakeshita
1Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan. yamanek@affrc.go.jp
Abstract:
Gram-positive sporulating Bacillus subtilis secretes high levels of protein. Its complete genome sequence, published in 1997, encodes 4,106 proteins. Bioinformatic searches have predicted that about half of all B. subtilis proteins are related to the cell membrane through export to the extracellular medium, insertion, and attachment. Key features of the B. subtilis protein secretion machinery are the absence of an Escherichia coli SecB homolog and the presence of an SRP (signal recognition particle) that is structurally rather similar to human SRP. In addition, B. subtilis contains five type I signal peptidases (SipS, T, U, V, and W). Our in vitro assay system indicated that co-operation between the SRP-protein targeting system to the cell membrane and the Sec protein translocation machinery across the cytoplasmic membrane constitutes the major protein secretion pathway in B. subtilis. Furthermore, the function of the SRP-Sec pathway in protein localization to the cell membrane and spore was analyzed.
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