From protein transport to organelle development

Ross Dalbey
YidC, a novel evolutionarily conserved protein, mediates membrane protein
assembly in bacteria
Membranes contain proteins that catalyze a variety of reactions, which lead to
the selective permeability of the membrane. For membrane proteins to function
as receptors, transporters, channels, and ATPases, they must be targeted to their
correct membrane and inserted into the lipid bilayer. Our goal is to understand
the biogenesis of polytopic membrane proteins in bacteria. While most E. coli
membrane proteins use the Sec YEG pathway for insertion into the plasma
membrane, there are some proteins that insert independent of the Sec pathway.
Recently we identified a new membrane component called YidC that is essential
for insertion of these Sec-independent proteins. YidC is essential for cell viability
and is found in mitochondria and chloroplasts. Depletion of YidC interferes also
with the insertion of Sec-dependent membrane proteins. We find that YidC
directly interacts with membrane proteins during the process of membrane
protein insertion. The chloroplast homolog Albino3 can functionally complement
the bacterial YidC depletion strain, demonstrating that the chloropast and
bacterial YidC homologs are truly functional homologs. The function of YidC for
Sec-independent proteins may be analogous to a chaperone because YidC has
been shown to bind and fold the inserting membrane proteins and not to interact
with the fully synthesized and assembled protein. For sec-dependent proteins,
YidC is proposed to catalyze the movement of hydrophobic regions out of the Sec
channel and into the lipid bilayer.
contact:
Professor Ross Dalbey
Ohio State University
Department of Chemistry
dalbey@chemistry.ohio-state.edu
100 West 18th Ave
43210 Columbus,OH (USA)