Cloning and DNA sequence of plasmid determinant iss, coding for increased serum survival and surface exclusion, which has homology with lambda DNA

Abstract

Escherichia coli K12 cells carrying a cloned 1.4 kb HindIII fragment from plasmid ColV2-K94, showed increased survival in guinea pig serum. The recombinant plasmid also conferred group II surface exclusion, i.e. the cells were reduced in recipient ability towards the incoming plasmid R538drd in conjugation experiments. Southern blotting suggested homology with bacteriophage lambda DNA and to the insertion element IS2. Determination of the DNA sequence of the fragment demonstrated the presence of a truncated IS2 (165 bp), separated by 250 bp from a 900 bp stretch of homology with lambda DNA, beginning within the Rz gene and continuing in the rightward direction on the lambda map. A 97 amino acid open reading frame (ORF) adjacent to Rz and on the opposite strand, remained intact in iss, with several amino acid changes. The ORF in iss is preceded by sequences resembling prokaryotic ribosome binding sites and promoters.

bor gene of phage lambda, involved in serum resistance, encodes a widely conserved outer membrane lipoprotein

“…This finding represents the first evidence that the open reading frame assigned to iss is in fact expressed as protein, and it confirms that Iss is closely related to Bor. It should be noted that Bor and the predicted Iss protein differ at 2 of the 12 C-terminal residues recognized by the peptide antibody: Bor, ...YTPLEARVYCSQ Iss, ...***R*T****** This difference was not noted in the iss sequence report, in which the DNA sequence appears to have been mistranslated at these two residues (13). The changes Leu3Arg and Ala3Thr indicate some tolerance for sequence variability in this epitope in our immunodetection experiments and suggest that the antibody used here could recognize other proteins which are slightly diverged from Bor.…”

“…Sequencing (13) has shown that iss displays a discrete block of 796 bp of DNA homology to covering the region from bp 46186 to 46982 in the sequence (50), which is at the 3Ј end of R Z , at the extreme right end of the genome. On either side of this region, homology to is not detectable.…”

“…It promotes an approximately 20-fold increase in survival of E. coli K-12 in animal serum in vitro and an approximately 100-fold increase in animal virulence of a non-K12 E. coli strain (3,13,14). We have shown that bor has the same in vitro effect as iss, promoting an approximately 20-fold increase in survival in animal serum on E. coli K-12 lysogens (2).…”

The Salmonella typhimurium virulence plasmid complement resistance gene rck is homologous to a family of virulence-related outer membrane protein genes, including pagC and ail

“…The S. typhimurium virulence plasmid traT allele, associated with serum resistance when introduced into rough, cured S. typhimurium, encodes a 27-kDa OMP (42). In addition, it has recently been determined that bacteriophage lambda contains a gene, designated bor, that is highly homologous to the iss serum resistance locus of the ColV2-K94 plasmid (1,6 high-level OmpX expression, was associated with a decrease in certain other OMPs greater than that expected by normalization of protein concentrations; in particular, the 43-kDa OMP appears to be decreased in Rck-containing strains (Fig. 2, lanes 3, 4, 7, 9, and 11).…”

Characterization of Monoclonal Antibodies to Avian Escherichia coli Iss

“…Iss, the protein product of iss, is thought to occur as a 10-11-kDa lipoprotein in the bacterial outer membrane (3,10). iss may be a derivative of bor, a gene of bacteriophage k (2,3,5,10). The blue open-reading (Bor) frame protein, a lipoprotein of the cell envelope of E. coli k lysogens, appears to confer complement resistance on these lysogens (2).…”