In vitro analysis of the bacterial twin-arginine-dependent protein export.

Prokaryotic organisms possess a specialized protein translocase in their cytoplasmic membranes that catalyzes the export of folded preproteins. Substrates for this pathway are distinguished by a twin-arginine consensus motif in their signal peptides (twin-arginine translocation [Tat] pathway). We have compiled detailed protocols for the preparation and operation of a cell-free system by which the bacterial Tat pathway can be fully reproduced in vitro. This system has proven useful and is being further exploited for the study of precursor-translocase interactions, assembly of the translocase, and the mechanism of transmembrane passage.