Molecular basis of Mycoplasma surface antigenic variation: a novel set of divergent genes undergo spontaneous mutation of periodic coding regions and 5' regulatory sequences.

摘要: Antigenic diversity is generated in the wall-less pathogen Mycoplasma hyorhinis by combinatorial expression and phase variation of multiple, size-variant membrane surface lipoproteins (Vlps). The unusual structural basis for Vlp was revealed a cluster related but divergent vlp genes, vlpA, vlpB vlpC, which occur as single chromosomal copies. These encode conserved N-terminal domains insertion lipoprotein processing, external undergoing size loss or gain repetitive intragenic coding sequences while retaining motif with distinctive charge distribution. Genetic analysis phenotypically switched isogenic lineages representing ON OFF states products ruled out rearrangement frameshift mutations mechanisms variation. However, highly promoter regions contain tract contiguous A residues immediately upstream -10 box subject to frequent altering its length exact correspondence specific genes. This suggests mechanism transcriptional control regulating high frequency random Vlps. multiple levels embodied gene represents novel adaptive capability particularly suited this class microbe.