Open AccessDistribution and Replication of the Pathogenicity Plasmid pPATH in Diverse Populations of the Gall-Forming Bacterium Pantoea agglomerans
Author(s) -
Dan Weinthal,
Isaac Barash,
Mary Panijel,
Lea Valinsky,
Victor Gaba,
Shulamit Manulis-Sasson
Publication year - 2007
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01511-07
Subject(s) - replicon , biology , plasmid , pantoea agglomerans , microbiology and biotechnology , genetics , escherichia coli , pathogenicity island , extrachromosomal dna , origin of replication , gene , bacteria
Pantoea agglomerans has been transformed from a commensal bacterium into two related gall-forming pathovars by acquisition of pPATH plasmids containing a pathogenicity island (PAI). This PAI harbors anhrp/hrc gene cluster, type III effectors, and phytohormone biosynthetic genes. DNA typing by pulsed-field gel electrophoresis revealed two major groups ofP. agglomerans pv. gypsophilae and one group ofP. agglomerans pv. betae. The pPATH plasmids of the different groups had nearly identical replicons (98% identity), and the RepA protein showed the highest level of similarity with IncN plasmid proteins. A series of plasmids, designated pRAs, in which the whole replicon region (2,170 bp) or deleted derivatives of it were ligated withnptI were generated for replicon analysis. A basic 929-bp replicon (pRA6) was sufficient for replication inEscherichia coli and in nonpathogenicP. agglomerans . However, the whole replicon region (pRA1) was necessary for expulsion of the pPATH plasmid, which resulted in the loss of pathogenicity. The presence of direct repeats in the replicon region suggests that the pPATH plasmid is an iteron plasmid and that the repeats may regulate its replication. The pPATH plasmids are nonconjugative but exhibit a broad host range, as shown by replication of pRA1 inErwinia, Pseudomonas , andXanthomonas . Restriction fragment length polymorphism analyses indicated that the PAIs in the two groups ofP. agglomerans pv. gypsophilae are similar but different from those inP. agglomerans pv. betae. The results could indicate that the pPATH plasmids evolved from a common ancestral mobilizable plasmid that was transferred into different strains ofP. agglomerans .