ISOLATION AND CHARACTERIZATION OF A LINKED CLUSTER OF GENES FROM AGROBACTERIUM-TUMEFACIENS ENCODING PROTEINS INVOLVED IN FLAGELLAR BASAL-BODY STRUCTURE

We report the DNA sequence of 7205 bp of the Agrobacterium tumefaciens chromosome. This contains a putative operon encoding homologues of th e flagellar rod and associated proteins FlgBCG and FliE, the L and P r ing proteins (FlgHI) a possible flagellum-specific export protein Flip , and two proteins of unknown function, FIgA and FliL. Several of thes e genes have overlapping stop and start codons. Three non-flagellate T n5-induced mutations map to this operon: fla-11 to the first gene, enc oding the rod protein FlgB; fla-15 to flgA; and fla-12 to fliL. A site -specific mutation introduced into the final gene in this cluster, fli P, also resulted in a non-flagellate phenotype. This indicates that th e operon is expressed, and that at least FlgB, FIgA, FliL and FliP are required for flagellar assembly in A. tumefaciens. The bulk of this o peron is conserved in the same order in Rhizobium meliloti.