Whitfield Chris
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Annu Rev Biochem. 2006;75:39-68. doi: 10.1146/annurev.biochem.75.103004.142545.
Capsules are protective structures on the surfaces of many bacteria. The remarkable structural diversity in capsular polysaccharides is illustrated by almost 80 capsular serotypes in Escherichia coli. Despite this variation, the range of strategies used for capsule biosynthesis and assembly is limited, and E. coli isolates provide critical prototypes for other bacterial species. Related pathways are also used for synthesis and export of other bacterial glycoconjugates and some enzymes/processes have counterparts in eukaryotes. In gram-negative bacteria, it is proposed that biosynthesis and translocation of capsular polysaccharides to the cell surface are temporally and spatially coupled by multiprotein complexes that span the cell envelope. These systems have an impact on both a general understanding of membrane trafficking in bacteria and on bacterial pathogenesis.
荚膜是许多细菌表面的保护性结构。大肠杆菌中近80种荚膜血清型说明了荚膜多糖显著的结构多样性。尽管存在这种变异，但用于荚膜生物合成和组装的策略范围有限，大肠杆菌分离株为其他细菌物种提供了关键的原型。相关途径也用于其他细菌糖缀合物的合成和输出，并且一些酶/过程在真核生物中有对应物。在革兰氏阴性细菌中，有人提出荚膜多糖的生物合成和转运到细胞表面是由跨越细胞膜的多蛋白复合物在时间和空间上耦合的。这些系统对细菌中膜运输的一般理解以及细菌致病性都有影响。
