The vsp Locus of Mycoplasma bovis: Gene Organization and Structural Features

摘要: Major lipoprotein antigens, known as variable membrane surface lipoproteins (Vsps), on the of bovine pathogen Mycoplasma bovis were shown to spontaneously undergo noncoordinate phase variation between ON and OFF expression states. The high rate Vsp phenotypic switching was also be linked with DNA rearrangements that occur at frequency in M. chromosome (I. Lysnyansky, R. Rosengarten, D. Yogev, J. Bacteriol. 178:5395-5401, 1996). In present study, 13 single-copy vsp genes organized a chromosomal cluster identified characterized. All encode highly conserved N-terminal domains for insertion processing but divergent mature proteins. About 80% each coding region is composed reiterated sequences create periodic polypeptide structure. Eighteen distinct repetitive different lengths amino acid are distributed within products various subject size due spontaneous insertions or deletions these units. Some repeats found only one family member, whereas other recurred locations several Vsps. Each gene 5' homologous upstream two internal cassettes. findings rearrangement events associated multiple regions sequence similarity suggest modulation antigenic repertoire determined by recombination processes locus bovis.