title: Pasteurella haemolytica serotype 2 contains the gene for a noncapsular serotype 1-specific antigen.
abstract: An ssa1-homologous genomic fragment cloned from Pasteurella haemolytica serotype 2 (ST2) enabled transformation of Escherichia coli DH5 alpha to a serotype 1 (ST1) phenotype through expression of the ST1-specific antigen (Ssa1). The Ssa1 protein expressed by ssa1-transformed E. coli was susceptible to heat and protease treatment and was distinct from P. haemolytica ST1-specific capsular polysaccharide. Electrophoretic analysis of in vitro-translated proteins, as well as the predicted amino acid sequence, demonstrated that Ssa1 proteins encoded from either ST1- or ST2-derived ssa1 genes were essentially identical. A comparison of the nucleotide sequences of ssa1 genes derived from P. haemolytica ST1 and ST2 revealed greater than 99% homology. Amino acid sequence homology of the predicted products of ST1- and ST2-derived ssa1 genes was greater than 98%. Northern (RNA) blot studies revealed that the presence of an increased level of ssa1 transcript in P. haemolytica ST1 grown as surface-adherent cultures on solid medium was correlated with a serologically detectable Ssa1 protein. Expression of the ssa1 transcript in ST1 was similarly upregulated by a high iron concentration in the growth medium.
authors.affiliation: Department of Veterinary PathoBiology, University of Minnesota, St. Paul 55108.
authors.forename: C T
authors.initials: CT
authors.lastname: Gonzalez
authors.forename: S K
authors.initials: SK
authors.lastname: Maheswaran
authors.forename: M P
authors.initials: MP
authors.lastname: Murtaugh
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007501:Iron / Q000494:pharmacology; D016978:Mannheimia haemolytica / Q000235:genetics* / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000276:immunology; D011994:Recombinant Proteins; D012995:Solubility; D014158:Transcription, Genetic
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D011135:Polysaccharides, Bacterial; D011994:Recombinant Proteins; D007501:Iron