1887

Abstract

The synthesis of extracellular enzymes and extracellular polysaccharide (EPS) in pathovar () is subject to co-ordinate regulation by a cluster of genes called (for egulation of athogenicity actors). These genes are located within a 219 kb region of the chromosome isolated as the cosmid clone pIJ3020. The genes in the left-hand section of this region of the chromosome have previously been characterized. This paper reports on the genes in the right-hand section and on the phenotypes of mutants with transposon insertions in these genes. Sequence analysis identified eight genes or ORFs with the gene order . RecJ and GreA have established functions in recombination and transcriptional elongation, respectively. encoded a protein with some amino acid sequence relatedness to a hypothetical protein from and an autolysin response regulator in . The predicted protein products of , and were related to each other and had substantial amino acid sequence relatedness to hypothetical proteins from . Transposon insertions in , and had no effect on the synthesis of extracellular enzymes or EPS. The predicted proteins RpfE and Orf4 showed the highest amino acid sequence relatedness to hypothetical proteins from and , respectively. Transposon insertions in led to reduced levels of some extracellular enzymes (endoglucanase and protease) and increased levels of others (polygalacturonate lyase). Transposon insertions in had no effect on polygalacturonate lyase but led to reduced levels of protease and endoglucanase. Levels of EPS were reduced in both and mutants. These alterations in the levels of extracellular enzymes, which were relatively modest (between two- and threefold), did not affect the pathogenicity of on turnip. It is proposed that the gene designation should be for .

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2000-04-01
2019-10-22
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