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 metaboli c functions in bacteria including the utilization of alternative carbon and nitrogen sources, nitrogen fixation, and the expression of virulence deter minants. Sequence analysis of a 3,020-bp DNA fragment from the plant pathog en Pseudomonas syringae pv. glycinea PG4180 revealed four ORFs designated r poN, orfA, orfB, and orfC Delta, which were related to rpoN and rpoN-associ ated genes from other micro-organisms. The rpoN upstream region in P. syrin gae contained two overlapping promoters, which may suggest a complex regula tory pattern. This is the first study describing the organization of the rp oN locus in P. syringae.