title: A cytoplasmic helix is required for pentamer formation of the Escherichia coli MscL mechanosensitive channel.
abstract: Many membrane proteins such as ion channels are oligomers, but the determinants of the degree of oligomerization are not fully understood. Mechanosensitive channel with large conductance (MscL), which is ubiquitous in bacteria, is a homopentamer with two transmembrane helices and a cytoplasmic helix in each subunit. The carboxyl-terminal cytoplasmic helices assemble into a pentameric bundle that resembles cartilage oligomeric matrix protein. To address the role of cytoplasmic helices in the pentamer formation of Escherichia coli MscL, we generated MscL constructs with various deletions at the carboxyl terminus and translated them in a cell-free system. Deletions of Leu-129 and the downstream sequence resulted in formation of various oligomers without preference to pentamers, suggesting that nearly the whole cytoplasmic helix is required for MscL pentamer formation.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Japan;
authors.forename: Chie
authors.initials: C
authors.lastname: Ando
authors.affiliation: Department of Biology, University of Maryland, 1210 Biology-Psychology Bldg., College Park, MD 20742, USA; and.
authors.forename: Naili
authors.initials: N
authors.lastname: Liu
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Japan; Department of Biology, University of Maryland, 1210 Biology-Psychology Bldg., College Park, MD 20742, USA; and Department of Machinery and Control Systems, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama 337-8570, Japan kenjiroy@shibaura-it.ac.jp.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Yoshimura
mesh_terms: D000595:Amino Acid Sequence; D003593:Cytoplasm / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D007473:Ion Channels / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D029968:Escherichia coli Proteins; D007473:Ion Channels; C086596:MscL protein, E coli
keywords: alpha-helix; ion channel; mechanosensitive channel; membrane protein; multimerization