The core of the bacterial translocase harbors a tilted transmembrane segment 3 of SecE.
The bacterial translocase mediates the translocation and membrane integration of proteins. The integral membrane proteins SecY and SecE are conserved core subunits of the translocase. Previous cysteine-scanning studies showed that the transmembrane segment (TMS) 3 of SecE contacts TMS 2 and 7 of SecY, and TMS 3 of another SecE. We now demonstrate that SecE also contacts TMS 10 of SecY. Combining all available cysteine-scanning mutagenesis data, a three-dimensional model has been built in which the positions of the helices that form the central core of the bacterial translocase are mapped. Remarkably, this model reveals that TMS 3 of SecE is strongly tilted relative to SecY.
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
Andreas K J
AK
Veenendaal
Chris
C
Van Der Does
Arnold J M
AJ
Driessen
D000595:Amino Acid Sequence; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003545:Cysteine / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D000069816:SEC Translocation Channels
D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C057841:SecY protein, E coli; D003545:Cysteine