A restriction map of virulence plasmid pVYE439-80 from a serogroup 9 Yersinia enterocolitica strain

A restriction map of the virulence plasmid pVYE439-80, isolated from Yersinia enterocolitica 439-80 (serogroup 9) was constructed for EcoRI, BamHI, SstII, and SmaI. The mapping was done after cloning of about two-thirds of the plasmid in Escherichia coli. The restriction pattern was compared to those obtained with plasmids isolated from Y. enterocolitica strains of serogroups 1, 3, and 5b. The restriction sites are particularly conserved in a region of about 25 kb. This region contains fragments that are also conserved in serogroup 8 strains [J. Heeseman, C. Keller, R. Morawa, N. Schmidt, H. J. Siemens, and R. Lauf (1983) J. Infect. Dis. 147, 107-115] and that were shown, in strains from this serogroup, to encode calcium dependency [D. A. Portnoy, H. Wolf-Watz, I. Bolin, A. B. Beeder, and S. Falkow, (1984) Infect. Immun. 43, 108-114]

Plasmid-encoded lysine decarboxylation in Proteus morganii.

As a rule, Proteus morganii does not decarboxylate lysine. However, lysine-positive P. morganii strains have been recently described. We suspected a plasmid origin for this atypical character, and we analyzed 14 strains to study this question. Among these strains, 8 yielded lysine-negative segregants after acridine orange or ethidium bromide treatment, and 10 transferred their lysine-positive character to a recipient P. morganii strain. All of the 14 strains analyzed at least segregated or conjugated. Three lysine-positive transconjugants, in turn, segregated lysine-negative variants after ethidium bromide treatment. The eight wild-type lysine-positive strains that segregated lysine-negative subclones contained a large (35 to 45 megadaltons) plasmid detectable by agarose gel electrophoresis. Similarly, the 10 lysine-positive transconjugants contained a plasmid of the same size, whereas P. morganii 1000, the recipient strain, did not contain any detectable plasmid. The large plasmid clearly disappeared in 9 of 11 lysine-negative segregants analyzed. It is concluded that the lysine-positive character of these P. morganii strains is plasmid encoded, and the taxonomical implications are discussed

Identification of Campylobacter jejuni and C. coli by gel electrophoresis of the outer membrane proteins.

Analysis of the electrophoretic profiles of the outer membrane proteins could be used to differentiate Campylobacter jejuni (16 strains) from Campylobacter coli (10 strains). This observation was confirmed by the study of DNA homology obtained by a quantitative filter hybridization method. The hippurate hydrolysis test gave a poor correlation with the results of differentiation obtained by DNA homology studies and outer membrane protein profile

The Yersinia yop regulon

Growth of yersiniae is restricted at 37 degrees C in the absence of calcium ions. This phenomenon correlates with the massive release of a set of proteins called Yops. Growth restriction and Yops production are governed by a 70 kb plasmid called pYV. yop genes are distributed throughout pYV and constitute a thermoactivated regulon controlled by the gene virF. The transcription activator VirF is a member of a new family of regulators including those of the arabinose and rhamnose operons as well as a regulator of enteric colonization pili. The role of calcium ions on the release of Yops remains largely unknown