title: Hydrophilic microenvironment required for the channel-independent insertase function of YidC protein.
abstract: The recently solved crystal structure of YidC protein suggests that it mediates membrane protein insertion by means of an intramembrane cavity rather than a transmembrane (TM) pore. This concept of protein translocation prompted us to characterize the native, membrane-integrated state of YidC with respect to the hydropathic nature of its TM region. Here, we show that the cavity-forming region of the stage III sporulation protein J (SpoIIIJ), a YidC homolog, is indeed open to the aqueous milieu of the Bacillus subtilis cells and that the overall hydrophilicity of the cavity, along with the presence of an Arg residue on several alternative sites of the cavity surface, is functionally important. We propose that YidC functions as a proteinaceous amphiphile that interacts with newly synthesized membrane proteins and reduces energetic costs of their membrane traversal.
authors: Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan;
authors: Naomi
authors: N
authors: Shimokawa-Chiba
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan;
authors: Kaoru
authors: K
authors: Kumazaki
authors: Department of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan; and Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
authors: Tomoya
authors: T
authors: Tsukazaki
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan;
authors: Osamu
authors: O
authors: Nureki
authors: Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan;
authors: Koreaki
authors: K
authors: Ito
authors: Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan; schiba@cc.kyoto-su.ac.jp.
authors: Shinobu
authors: S
authors: Chiba
mesh_terms: D001120:Arginine / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D005033:Ethylmaleimide / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014867:Water / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C412443:YIDC protein, E coli; C030069:spore-specific proteins, Bacillus; D014867:Water; D001120:Arginine; D005033:Ethylmaleimide
keywords: MifM; Oxa1; SpoIIIJ; YidC; membrane protein insertion