Liu D, Verma N K, Romana L K, Reeves P R
Department of Microbiology, University of Sydney, New South Wales, Australia.
J Bacteriol. 1991 Aug;173(15):4814-9. doi: 10.1128/jb.173.15.4814-4819.1991.
The O antigens of Salmonella serogroups A, B, and D differ structurally in their side chain sugar residues. The genes encoding O-antigen biosynthesis are clustered in the rfb operon. The gene rfbJ in strain LT2 (serovar typhimurium, group B) and the genes rfbS and rfbE in strain Ty2 (serovar typhi, group D) account for the known differences in the rfb gene clusters used for determination of group specificity. In this paper, we report the nucleotide sequence of 2.9 kb of DNA from the rfb gene cluster of strain Ty2 and the finding of two open reading frames which have limited similarity with the corresponding open reading frames of strain LT2. These two genes complete the sequence of the rfb region of group D strain Ty2 if we use strain LT2 sequence where restriction site data show it to be extremely similar to the strain Ty2 sequence. The restriction map of the rfb gene cluster in group A strain IMVS1316 (serovar paratyphi) is identical to that of the cluster in strain Ty2 except for a frameshift mutation in rfbE and a triplicated region. The rfb gene clusters of these three strains are compared, and the evolutionary origin of these genes is discussed.
沙门氏菌A、B和D血清群的O抗原在其侧链糖残基的结构上存在差异。编码O抗原生物合成的基因聚集在rfb操纵子中。LT2菌株（鼠伤寒血清型，B群）中的rfbJ基因以及Ty2菌株（伤寒血清型，D群）中的rfbS和rfbE基因解释了用于确定群特异性的rfb基因簇中的已知差异。在本文中，我们报告了Ty2菌株rfb基因簇中2.9 kb DNA的核苷酸序列，并发现了两个与LT2菌株相应开放阅读框具有有限相似性的开放阅读框。如果我们使用LT2菌株序列（在限制酶切位点数据显示其与Ty2菌株序列极其相似的情况下），这两个基因完善了D群菌株Ty2的rfb区域序列。A群菌株IMVS1316（副伤寒血清型）中rfb基因簇的限制酶切图谱与Ty2菌株中的图谱相同，只是rfbE中存在一个移码突变和一个重复区域。对这三个菌株的rfb基因簇进行了比较，并讨论了这些基因的进化起源。
