Lee S J, Romana L K, Reeves P R
Department of Microbiology, University of Sydney, NSW, Australia.
J Gen Microbiol. 1992 Feb;138(2):305-12. doi: 10.1099/00221287-138-2-305.
The Salmonella enterica group C1 O antigen structure has a Man-Man-Man-Man-GlcNAc backbone with a glucose branch, which differs from the S. enterica group B O antigen structure which has a Man-Rha-Gal backbone with abequose as side-chain. We have cloned the group C1 rfb (O antigen) gene cluster from serovar montevideo strain M40, using a low-copy-number cosmid vector. The restriction map of the group C1 (M40) rfb gene cluster was compared with that of group B strain LT2 by Southern hybridization and restriction enzyme analysis. The results indicate that the flanking genes are very similar in the two strains, but there is no detectable similarity in the rfb regions. We localized the mannose pathway genes rfbM and rfbK and one of the genes, rfbK, shows considerably similarity to cpsG of strain LT2, suggesting that part of the mannose pathway in the group C1 rfb cluster is derived from a gene of the M antigen (cps) cluster. The M antigen, which forms a capsule, is comprised of four sugars, including fucose. The biosynthetic pathway of GDP-fucose has steps in common with the GDP-mannose pathway, and the cps cluster has isogenes of rfbK and rfbM, presumably as part of a fucose pathway. We discuss the structure and possible evolution of the group C1 rfb gene cluster.
肠炎沙门氏菌C1群O抗原结构具有一条带有葡萄糖分支的甘露糖-甘露糖-甘露糖-甘露糖-N-乙酰葡糖胺主链，这与肠炎沙门氏菌B群O抗原结构不同，后者具有一条带有阿比可糖作为侧链的甘露糖-鼠李糖-半乳糖主链。我们使用低拷贝数黏粒载体从蒙得维的亚血清型菌株M40中克隆了C1群rfb（O抗原）基因簇。通过Southern杂交和限制性内切酶分析，将C1群（M40）rfb基因簇的限制性图谱与B群菌株LT2的进行了比较。结果表明，两株菌的侧翼基因非常相似，但rfb区域没有可检测到的相似性。我们定位了甘露糖途径基因rfbM和rfbK，其中一个基因rfbK与LT2菌株的cpsG有相当程度的相似性，这表明C1群rfb簇中甘露糖途径的一部分源自M抗原（cps）簇的一个基因。形成荚膜的M抗原由四种糖组成，包括岩藻糖。GDP-岩藻糖的生物合成途径与GDP-甘露糖途径有共同步骤，并且cps簇有rfbK和rfbM的同系基因，大概是岩藻糖途径的一部分。我们讨论了C1群rfb基因簇的结构和可能的进化。
