Analysis of the rpoN Locus in the Plant Pathogenic Bacterium, Pseudomonas Syringae pv. Glycinea

sigma 54, which is encoded by rpoN, is required for a variety of metabolic functions in bacteria including the utilization of alternative carbon and nitrogen sources, nitrogen fixation, and the expression of virulence determinants. Sequence analysis of a 3,020-bp DNA fragment from the plant pathogen Pseudomonas syringae pv. glycinea PG4180 revealed four ORFs designated rpoN, orfA, orfB, and orfC delta, which were related to rpoN and rpoN-associated genes from other microorganisms. The rpoN upstream region in P. syringae contained two overlapping promoters, which may suggest a complex regulatory pattern. This is the first study describing the organization of the rpoN locus in P. syringae.