We report that phosphatidylglycerol is required for flagellation of Escherichia coli. Cells carrying the pgsA3 mutation did not form swarm rings in semisolid agar. P1 transduction experiments revealed that the potential for phosphatidylglycerol synthesis and for the formation of swarm rings was co-transducible. The pgsA3 mutant transformed with the wild type pgsA + gene cloned into the R-plasmid vector had the potential for both phosphatidylglycerol synthesis and cell motility. Electronmicroscopic and SDS-PAGE analyses showed that the pgsA3 mutation causes the lack of flagellation.
