TCB Publications - Abstract

James Gumbart and Klaus Schulten. Molecular dynamics studies of the archaeal translocon. Biophysical Journal, 90:2356-2367, 2006. (PMC: 1403164)

GUMB2006 The translocon is a protein-conducting channel conserved over all domains of life that serves to translocate proteins across or into membranes. While this channel has been well-studied for many years, the recent discovery of a high- resolution crystal structure opens up new avenues of exploration. Taking advantage of this, we performed molecular dynamics simulations of the translocon in a fully-solvated lipid bilayer, examining the translocation abilities of monomeric SecYE$\beta$ by forcing two helices comprised of different amino acid sequences to cross the channel. The simulations revealed that the so-called `plug' of SecYE$\beta$ swings open during translocation, closing thereafter. Likewise, it was established that the so-called `pore ring' region of SecYE$\beta$ forms an elastic, yet tight seal around the translocating oligopeptides. The closed state of the channel was found to block permeation of all ions and water molecules; in the open state, ions were blocked. Our results suggest that the SecYE$\beta$ monomer is capable of forming an active channel.

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