YidC and SecYEG form a heterotetrameric protein translocation channel
Sprache des Titels:
The heterotrimeric SecYEG cooperates with YidC to facilitate Membrane Protein Insertion by an unknown mechanism. Here we Show that YidC contacts the interior of the SecY channel resulting in a Ligand-activated and voltage-dependent complex with distinct ion channel characteristics. The SecYEG pore diameterdecreases from 8A to only 5A for the YidC-SecYEG pore, indicating a reduction in channel cross section by YidC intercalation. In the presence of a substrate, YidC relocates to the rim of a pore as indicated by increased pore Diameter and loss of YidC crosslinks to the channel interior. Changing the surface charge of the pore by incorporating YidC into the channel wall increases the anion selectivity and the accompanying change in wall hydrophobicity is liable to alter the partition of Helices from the pore into the membrane. This could explain how the exit of transmembrane domains from SecY channel is facilitated by YidC.