Conservation and variation of nucleotide sequences within related bacterial genomes: enterobacteria

We have assessed the degree of relatedness of several portions of the Escherichia coli genome to the corresponding portions of the genomes of representative enteric bacteria, using the Southern transfer and hybridization technique (E. Southern, J. Mol. Biol. 98:503-517, 1975). The degree of relatedness varied among the regions examined. Judging both by the relative amounts of deoxyribonucleic acid in the various enteric genomes that are highly homologous and by the conservation of positions of restriction enzyme cleavage sites in these regions, the enteric genomes have diverged to greater extents in some parts of the genomes than in others. Portions of the genomes (including the tnaA and thyA genes, the trp operon, and one other unassigned segment) appear to have evolved in concert with the genome as a whole. By contrast, the lacZ gene and portions of the genome that are homologous to phage lambda vary more widely, perhaps reflecting a separate evolutionary origin for these segments of deoxyribonucleic acid.</jats:p

Conservation and variation of nucleotide sequences within related bacterial genomes: Escherichia coli strains

Changes in the patterns produced by annealing restriction endonuclease digests of bacterial genomes with probe deoxyribonucleic acids (DNAs) containing small portions of a bacterial genome provide sensitive indicator of the degree of nucleotide sequence relatedness that exists in localized regions of the genomes of closely related bacteria. We have used five probe DNAs to explore the relatedness of parts of the genomes of six laboratory Escherichi coli strains. A range in in the amount of variability in the positions of restriction enzyme cleavage sites in the selected portions of the genomes was found. Portions of the genome that are believed to be inacative were more variable than portions that contained functional genes: the sites in and near regions of homology to phage lambda DNA in the genome showed the greatest variability. These regions probably represent remnants of cryptic prophages. Variability was assessed pairwise among four of the E. coli strains and ranged from 5 to &gt; 25% base pair substitutions in the lambda-related regions. In contrast, the endonuclease cleavage sites in the trp, tna, lac, thy regions, and one other as-yet-unidentified segment of the genome were more highly conserved. It seems likely that these sites lie in genetic locations that are subject to functional constraints.</jats:p

Homology between the glycoproteins of vesicular stomatitis virus and rabies virus

We compared the predicted amino acid sequences of the vesicular stomatitis virus and rabies virus glycoproteins by using a computer program which provides an optimal alignment and a statistical significance for the match. Highly significant homology between these two proteins was detected, including identical positioning of one glycosylation site. A significant homology between the predicted amino acid sequences of vesicular stomatitis virus and influenza virus matrix proteins was also found.</jats:p

Antigenic conservation of the 15,000-dalton outer membrane lipoprotein PCP of Haemophilus influenzae and biologic activity of anti-PCP antisera

A gene from Haemophilus influenzae encoding an outer membrane lipoprotein of about 15,000 daltons and which comigrates with the peptidoglycan-associated lipoprotein (PAL) of H. influenzae on sodium dodecyl sulfate-polyacrylamide gel electrophoresis has been previously reported and designated pcp gene, and its product has been designated PCP. in order to obtain specific immunologic probes for the analysis of PCP expression, cellular location, and antigenic conservation in H. influenzae, pcp was fused to the lac polylinker region of plasmid pUC19 and the hybrid gene was expressed in Escherichia coli. PCP purified from these cells was used to generate rabbit and mouse polyclonal antisera and mouse monoclonal antibody against PCP. Western immunoblot analysis with anti-PCP monoclonal antibody demonstrated that PCP is present and antigenically conserved in 30 tested strains of H. influenzae, including 27 clinical nontypeable strains. Polyclonal antiserum against PCP killed 9 of 11 clinical H. influenzae strains in a complement-mediated bactericidal assay, and bactericidal activity was additive with bactericidal activity of antisera against PAL. These results indicate that PCP is a potentially valuable component for a subunit vaccine against nontypeable H. influenzae disease, especially in combination with PAL or other components.</jats:p