title: Weak pulling forces exerted on Nin-orientated transmembrane segments during co-translational insertion into the inner membrane of Escherichia coli.
abstract: Transmembrane helices (TMHs) in membrane proteins can be orientated with their N-terminus towards the cytoplasm (Nin), or facing the non-cytoplasmic side (Nout). Most membrane proteins are inserted co-translationally into membranes, aided by Sec-type translocons. Since the final orientation of Nin- and Nout-orientated TMHs differs, they could also interact differently with the translocon and the surrounding membrane during insertion. We measured pulling forces exerted on Nin-orientated TMHs during co-translational insertion into the inner membrane of Escherichia coli. Our results demonstrate that Nin-orientated TMHs experience a weaker pulling force but retain the overall biphasic force profile seen previously for Nout-orientated TMHs (Ismail et al., 2012 [1]).
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Florian
authors.initials: F
authors.lastname: Cymer
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Nurzian
authors.initials: N
authors.lastname: Ismail
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Science for Life Laboratory, Stockholm University, Box 1031, SE-171 21 Solna, Sweden. Electronic address: gunnar@dbb.su.se.
authors.forename: Gunnar
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D014176:Protein Biosynthesis; D017433:Protein Structure, Secondary; D021381:Protein Transport; D012689:Sequence Homology, Nucleic Acid
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins
keywords: Membrane insertion; Transmembrane helix; Type 2 membrane protein