title: Transposition of structural genes to an expression sequence on a linear plasmid causes antigenic variation in the bacterium Borrelia hermsii.
abstract: In Borrelia hermsii, a spirochaete that causes relapsing fever, the switch between expression of two frequent variable major protein (VMP) types (7 and 21) is associated with a DNA rearrangement. Both cell types 7 and 21 contain untranscribed 7 and 21 VMP genes on linear plasmids. The serotype 7 cells contain an additional copy of the 7 VMP gene fused to an expression sequence on another linear plasmid. Switching to the 21 serotype involves removal of the transcribed 7 VMP gene and fusion of a copy of the 21 VMP gene to this same expression sequence. Thus recombination between linear plasmids can activate different VMP genes.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D001898:Borrelia / Q000235:genetics*; D005796:Genes; D014644:Genetic Variation; D010957:Plasmids; D011995:Recombination, Genetic
chemical_list: D001426:Bacterial Proteins