YidC protein, a molecular chaperone for LacY protein folding via the SecYEG protein machinery.
To understand how YidC and SecYEG function together in membrane protein topogenesis, insertion and folding of the lactose permease of Escherichia coli (LacY), a 12-transmembrane helix protein LacY that catalyzes symport of a galactoside and an H(+), was studied. Although both the SecYEG machinery and signal recognition particle are required for insertion of LacY into the membrane, YidC is not required for translocation of the six periplasmic loops in LacY. Rather, YidC acts as a chaperone, facilitating LacY folding. Upon YidC depletion, the conformation of LacY is perturbed, as judged by monoclonal antibody binding studies and by in vivo cross-linking between introduced Cys pairs. Disulfide cross-linking also demonstrates that YidC interacts with multiple transmembrane segments of LacY during membrane biogenesis. Moreover, YidC is strictly required for insertion of M13 procoat protein fused into the middle cytoplasmic loop of LacY. In contrast, the loops preceding and following the inserted procoat domain are dependent on SecYEG for insertion. These studies demonstrate close cooperation between the two complexes in membrane biogenesis and that YidC functions primarily as a foldase for LacY.
From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210 and.
Lu
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Zhu
H Ronald
HR
Kaback
Ross E
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Dalbey
D004220:Disulfides / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010447:Peptide Hydrolases / Q000737:chemistry; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D000069816:SEC Translocation Channels; D027981:Symporters / Q000378:metabolism*
D004220:Disulfides; D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D009004:Monosaccharide Transport Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli; D027981:Symporters; C412443:YIDC protein, E coli; D010447:Peptide Hydrolases
Chaperone; Chaperonin; LacY; Membrane Biogenesis; Membrane Enzymes; Membrane Insertion; Membrane Proteins; Protein Folding; YidC