Plasmid Structure and Function in Plant-Pathogenic Pseudomonas Syringae (outer-Membrane Proteins)

145 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.Thirty isolates of Pseudomonas syringae pv/ tabaci, pv. angulata, (pathogens on tobacco) pv. coronafaciens, and pv. striafaciens (pathogens on oat) were examined for plasmid DNAs. The strains were obtained from plants throughout the world and some over 30 years ago. Sixteen of the twenty-two tobacco pathogens contain predominately one type of plasmid species, pJP27.00-type. The remaining six tobacco-specific strains do not harbor plasmids. The oat pathogens contain either one, two or three plasmids. DNA homology studies indicate, that the plasmid DNAs are highly conserved. More importantly, the plasmids harbored by strains isolated from one host plant are most stringently conserved. In fact, the plasmids from the tobacco pathogens are, with one exception, indistinguishable by restriction endonuclease digestions and Southern hybridization. There is also extensive homology among plasmids indigenous to the oat-specific Pseudomonas syringae pv. coronafiens and pv. striafaciens strains. However, some of the multiple plasmids within an individual strain are unrelated.Outer membranes of plant-pathogenic Pseudomonas syringae pv. tabaci strains were examined for protein composition based upon plasmid (pBPW1) presence and absence. Sodium dodecyl sulfate polyacrylamide gel electrophoretic resolution of solubilized outer membranes purified on sucrose density gradients identifies an approximately 33,000 dalton protein that is present in cells harboring pBPW1 plasmid. In vitro plasmid DNA-directed transcription and translation experiments establish that the structural gene for this 33,000 dalton protein is located on the pBPW1 plasmid. The expression of this 33,000 dalton protein is eliminated by a Tn3 insertion into the PstI fragment of pBPW1. The third, fourth, and fifth PstI fragment of pBPW1 have been ligated into pWS6 vector plasmid. None of the chimeric plasmids express this 33,000 dalton protein in the Pseudomonas syringae pv. tabaci strain that was transformed separately with the chimeric plasmids. However, the fusion plasmid containing the fourth PstI fragment produces a smaller, approximately 24,000 dalton outer membrane protein. In vitro plasmid DNA-directed transcription translations suggest that this is a second outer membrane protein that is not detectable by the sodium dodecyl sulfate polyacrylamide gel electrophoretic resolution of purified membranes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD