FlaK of the archaeon Methanococcus maripaludis possesses preflagellin peptidase activity.

Archaeal flagellins are initially synthesized as preflagellins with a short, positively charged leader peptide, which is cleaved prior to the incorporation of the mature flagellins into the filament. While preflagellin peptidase activity had previously been detected in methano-en membranes, the enzyme responsible for this activity had not been identified. We show here that FlaK of Methanococcus maripaludis has preflagellin peptidase activity, In an in vitro preflagellin peptidase assay, Escherichia coli membranes overexpressing Methanococcus voltae preflagellin FlaB2 (as substrate) were combined with E. coli membranes overexpressing M. maripaludis FlaK (as enzyme). Cleavage of the preflagellin was demonstrated by immunoblotting using antibody to Fla132 and detection of a faster migrating cross-reactive species. This activity required detergent in the assay, and was not detected in membranes previously heated to 95degreesC. This is the first reported identification of the preflagellin peptidase, and aside from the flagellins, this is the first assignment of function to a gene involved in archaeal flagellation. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.