Antigenic and genetic characterisation of lipoprotein lppC from Mycoplasma mycoides subsp. mycoides SCPaola Piloa, Sandra Martigb, Joachim Freya and Edy M. Vileia
a Institute for Veterinary Bacteriology, University of Berne, Laenggassstrasse 122, 3012 Berne, Switzerland
b Clinic for Small Animals, University of Berne, Laenggassstrasse 124, 3012 Berne, Switzerland
(Received 22 November 2002; accepted 29 April 2003)
Lipoprotein lppC, an immunodominant antigen, and its corresponding gene lppC were characterised in Mycoplasma mycoides subspecies mycoides small colony (SC) type, the etiological agent of contagious bovine pleuropneumonia (CBPP). The lppC gene was found in the type strain of M. mycoides subsp. mycoides SC and in field strains isolated in Europe, Africa, and Australia, as well as in vaccine strains. Southern blot analysis indicated the presence of at least four copies of lppC in the genome of M. mycoides subsp. mycoides SC, of which only one seems to be functional. Genes homologous to lppC have also been detected in closely related mycoplasmas such as M. mycoides subsp. mycoides large colony (LC) type and in M. sp. bovine group 7. lppC is encoded as a precursor with a consensus sequence for a prokaryotic signal peptidase II. The amino acid sequence of lppC and its precursor showed similarity to both LppB (at the N-terminal domain) and LppQ (at the C-terminal domain), two lipoproteins described previously in M. mycoides subsp. mycoides SC. The N-terminal domain of the mature lppC seems to be surface exposed. The C-terminal domain presented an integral membrane structure made up of five repeated units, rich in hydrophobic and aromatic amino acids, which may have pore forming potential in the mycoplasmal membrane. A recombinant peptide representing the N-terminal half of lppC was obtained following cloning in vector pETHIS-1 and expression in Escherichia coli hosts. The recombinant protein was used on immunoblots for serological analysis of sera from cattle that were naturally or experimentally infected with M. mycoides subsp. mycoides SC.
Key words: Mycoplasma mycoides subsp. mycoides SC / contagious bovine pleuropneumonia / multiple copy gene / antigenic protein / lipoprotein
Correspondence and reprints: Edy M. Vilei email@example.com
© INRA, EDP Sciences 2003