Stevenson B, Zückert W R, Akins D R
Department of Microbiology and Immunology, Chandler Medical Center, University of Kentucky College of Medicine, Lexington 40536-0298, USA.
J Mol Microbiol Biotechnol. 2000 Oct;2(4):411-22.
Members of the spirochete genus Borrelia contain large numbers of extrachromosomal DNAs. Sequence analysis of the B. burgdorferi strain B31 genome indicated that its many plasmids contain large quantities of repeated sequences, the most obvious of which are the cp32 plasmid family. Individual spirochetes may carry nine or more different, but homologous, cp32 plasmids. Every other species of Borrelia examined thus far also contains multiple plasmids related to the B. burgdorferi cp32s. These plasmids are arguably the best characterized of all the borrelial plasmids, and epitomize the apparent redundancy evident in the many plasmids carried by these bacteria. Despite their extensive similarities, cp32 plasmids contain some open reading frames whose sequences often vary between plasmids, and which encode proteins synthesized by the bacteria during vertebrate infection. In this review, we analyze the hypervariable and conserved regions of the cp32 plasmid family, and discuss possible reasons why borreliae harbor multiple gene paralogs.
螺旋体属的伯氏疏螺旋体成员含有大量的染色体外DNA。对伯氏疏螺旋体B31菌株基因组的序列分析表明，其众多质粒包含大量重复序列，其中最明显的是cp32质粒家族。单个螺旋体可能携带九个或更多不同但同源的cp32质粒。迄今为止检测的其他伯氏疏螺旋体物种也含有与伯氏疏螺旋体cp32相关的多个质粒。这些质粒可以说是所有伯氏疏螺旋体质粒中特征最明确的，并且体现了这些细菌携带的许多质粒中明显的冗余现象。尽管cp32质粒有广泛的相似性，但它们包含一些开放阅读框，其序列在不同质粒之间经常变化，并且编码细菌在脊椎动物感染期间合成的蛋白质。在这篇综述中，我们分析了cp32质粒家族的高变区和保守区，并讨论了伯氏疏螺旋体携带多个基因旁系同源物的可能原因。
