title: Quantitative analysis of SecYEG-mediated insertion of transmembrane α-helices into the bacterial inner membrane.
abstract: Most integral membrane proteins, both in prokaryotic and eukaryotic cells, are co-translationally inserted into the membrane via Sec-type translocons: the SecYEG complex in prokaryotes and the Sec61 complex in eukaryotes. The contributions of individual amino acids to the overall free energy of membrane insertion of single transmembrane α-helices have been measured for Sec61-mediated insertion into the endoplasmic reticulum (ER) membrane (Nature 450:1026-1030) but have not been systematically determined for SecYEG-mediated insertion into the bacterial inner membrane. We now report such measurements, carried out in Escherichia coli. Overall, there is a good correlation between the results found for the mammalian ER and the E. coli inner membrane, but the hydrophobicity threshold for SecYEG-mediated insertion is distinctly lower than that for Sec61-mediated insertion.
authors: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden.
authors: Karin
authors: K
authors: Ojemalm
authors: Salomé Calado
authors: SC
authors: Botelho
authors: Chiara
authors: C
authors: Stüdle
authors: Gunnar
authors: G
authors: von Heijne
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D000069816:SEC Translocation Channels; D013816:Thermodynamics
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli
keywords: EDTA; ER; IM; SecYEG; TMH; endoplasmic reticulum; ethylenediaminetetraacetic acid; inner membrane; leader peptidase; membrane protein; transmembrane helix