Use of nonmotile mutants to identify a set of membrane proteins related to gliding motility in Cytophaga johnsonae.

Nonmotile mutants of the gliding bacterium Cytophaga johnsonae were examined to identify proteins that might be involved in gliding motility. Wild-type and mutant cell proteins were solubilized and fractionated by using Triton X-114, and the proteins that partitioned into the aqueous phase or the detergent phase were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for proteins that differed between wild-type and mutant cells. Seventeen proteins, ranging in size from 16 to 150 kilodaltons, were implicated by this technique as having some relationship to gliding and were designated Gld-1 through Gld-17. All Gld proteins behaved as integral membrane proteins, partitioning into the detergent phase. All 56 mutants examined exhibited changes in 1 or more of the Gld proteins, with the number of proteins altered in any mutant varying from 1 to 11. Several lines of evidence suggested that proteins Gld-12 through Gld-15 are glycoproteins. Analysis of banding patterns of detergent-fraction proteins of motile revertants supported the idea that the Gld proteins have a role in gliding motility.