A PLEIOTROPIC REDUCED VIRULENCE (RVI-) MUTANT OF ERWINIA-CAROTOVORA SUBSPECIES ATROSEPTICA IS DEFECTIVE IN FLAGELLA ASSEMBLY PROTEINS THAT ARE CONSERVED IN PLANT AND ANIMAL BACTERIAL PATHOGENS

Erwinia carotovora subsp. atroseptica was mutagenized and assayed for virulence in planta. Those mutants which exhibited reduced virulence ( Rvi-) were assayed for growth rate, auxotrophy and extracellular enzym e secretion and seven mutants were found to be wild type for all of th ese phenotypes. When screened for other phenotypes, two were found to be non-motile. One mutant was complemented for motility by a heterolog ous gene library. A 2.7 kb XmaIII-ClaI complementing fragment was sequ enced and the gene products were found to have similarity to flagella biosynthesis gene products from several bacteria. Further similarity w as found to a pathogenicity protein from the plant pathogen Xanthomona s campestris pv. glycines and to the Spa pathogenicity proteins of the human pathogen Shigella flexneri, which are involved in the surface p resentation of antigens. These studies highlight the emergence of comm on themes in the molecular strategies employed by both plant and anima l bacterial pathogens for the targeting of proteins involved in the el aboration of disease.