Long-timescale dynamics and regulation of Sec-facilitated protein translocation.

ABSTRACT: We present a coarse-grained modeling approach that spans the nanosecond- to minute-timescale dynamics of cotranslational protein translocation. The method enables direct simulation of both integral membrane protein topogenesis and transmembrane domain (TM) stop-transfer efficiency. Simulations reveal multiple kinetic pathways for protein integration, including a mechanism in which the nascent protein undergoes slow-timescale reorientation, or flipping, in the confined environment of the translocon channel. Competition among these pathways gives rise to the experimentally observed dependence of protein topology on ribosomal translation rate and protein length. We further demonstrate that sigmoidal dependence of stop-transfer efficiency on TM hydrophobicity arises from local equilibration of

SUBMITTER: Zhang B 

PROVIDER: S-EPMC3483636 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature