Rd. Frederick et al., IDENTIFICATION OF A PATHOGENICITY LOCUS, RPFA, IN ERWINIA-CAROTOVORA SUBSP CAROTOVORA THAT ENCODES A 2-COMPONENT SENSOR-REGULATOR PROTEIN, Molecular plant-microbe interactions, 10(3), 1997, pp. 407-415
A mutant of Erwinia carotovora subsp. carotovora, AH2552, created by a
Mud1 insertion was found to be reduced in plant pathogenicity and def
icient in extracellular protease and cellulase activity, although it p
roduced normal levels of pectate lyase and polygalacturonase. A cosmid
clone, pEC462, was isolated from a wild-type E. carotovora subsp, car
otovora DNA library that concomitantly restored pathogenicity and prot
ease and cellulase activities of AH2552 to wild-type levels when prese
nt in trans. The genetic locus that was disrupted in AH2552 by inserti
on of Mud1 has been designated rpfA, for regulator of pathogenicity fa
ctors. Sequencing of the rpfA region identified an open reading frame
of 2,787 bp, and the predicted 929-amino acid polypeptide shared high
identity with several two-component sensor-regulator proteins: BarA fr
om Escherichia coli, ApdA from Pseudomonas fluorescens, PheN from P. t
olaasii, RepA from P. viridiflava, LemA from P. syringae pv. syringae,
and RpfC from Xanthomonas campestris pv. campestris. The RpfA locus d
escribed in this study encodes a putative sensor kinase protein that i
s involved in both extracellular protease and cellulase production and
the pathogenicity of E. carotovora subsp. carotovora on potato tubers
.