CHARACTERIZATION OF A 4TH LIPOPROTEIN FROM PASTEURELLA-HAEMOLYTICA A1AND ITS HOMOLOGY TO THE OMPA FAMILY OF OUTER-MEMBRANE PROTEINS

A fourth lipoprotein gene from Pasteurella haemolytica Al was cloned a nd characterized. The plpD gene encodes a 31-kDa lipoprotein (Plp4) wh ich could be recognized in Western immunoblot by sera from calves immu nized with the culture supernatant vaccine Presponse. This suggests th at Plp4 is one of the immunogenic molecules in the P. haemolytica Al c ulture supernatant. The lipoprotein nature of Plp4 was confirmed by la belling with [H-3]palmitate and inhibition of leader peptide cleavage with globomycin. A homology search with databanks showed extensive hom ology between Plp4 and a 31-kDa antigen from Haemophilus somnus and a 19.2-kDa antigen from Neisseria meningitidis. Additional homology of t he distal half of Plp4 was identified with a number of bacterial outer membrane proteins belonging to the OmpA family. Plp4 appears to be a novel type of outer membrane protein that contains motifs typical of O mpA but which is also lipid modified. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All righ ts reserved.