title: Structural basis of Sec-independent membrane protein insertion by YidC.
abstract: Newly synthesized membrane proteins must be accurately inserted into the membrane, folded and assembled for proper functioning. The protein YidC inserts its substrates into the membrane, thereby facilitating membrane protein assembly in bacteria; the homologous proteins Oxa1 and Alb3 have the same function in mitochondria and chloroplasts, respectively. In the bacterial cytoplasmic membrane, YidC functions as an independent insertase and a membrane chaperone in cooperation with the translocon SecYEG. Here we present the crystal structure of YidC from Bacillus halodurans, at 2.4 Å resolution. The structure reveals a novel fold, in which five conserved transmembrane helices form a positively charged hydrophilic groove that is open towards both the lipid bilayer and the cytoplasm but closed on the extracellular side. Structure-based in vivo analyses reveal that a conserved arginine residue in the groove is important for the insertion of membrane proteins by YidC. We propose an insertion mechanism for single-spanning membrane proteins, in which the hydrophilic environment generated by the groove recruits the extracellular regions of substrates into the low-dielectric environment of the membrane.
authors.affiliation: 1] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan [3].
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kumazaki
authors.affiliation: 1] Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan [2].
authors.forename: Shinobu
authors.initials: S
authors.lastname: Chiba
authors.affiliation: 1] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Takemoto
authors.affiliation: Department of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
authors.forename: Arata
authors.initials: A
authors.lastname: Furukawa
authors.affiliation: Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Nishiyama
authors.affiliation: Department of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sugano
authors.affiliation: Theoretical Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Takaharu
authors.initials: T
authors.lastname: Mori
authors.affiliation: Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Dohmae
authors.affiliation: SR Life Science Instrumentation Unit, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Hirata
authors.affiliation: Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Nakada-Nakura
authors.affiliation: Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Andrés D
authors.initials: AD
authors.lastname: Maturana
authors.affiliation: Department of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Institute for Virus Research, Kyoto University, Shogoin Kawara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mori
authors.affiliation: Theoretical Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sugita
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Arisaka
authors.affiliation: Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.
authors.forename: Koreaki
authors.initials: K
authors.lastname: Ito
authors.affiliation: 1] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Ishitani
authors.affiliation: 1] Department of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan [2] JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Tsukazaki
authors.affiliation: 1] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Nureki
mesh_terms: D001120:Arginine / Q000378:metabolism; D001407:Bacillus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D001120:Arginine
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