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首页> 外文期刊>Journal of bacteriology >Relationships between rfb gene clusters required for biosynthesis of identical D-galactose-containing O antigens in Klebsiella pneumoniae serotype O1 and Serratia marcescens serotype O16.
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Relationships between rfb gene clusters required for biosynthesis of identical D-galactose-containing O antigens in Klebsiella pneumoniae serotype O1 and Serratia marcescens serotype O16.

机译：生物合成肺炎克雷伯菌血清型O1和粘质沙雷氏菌血清型O16中的相同D-半乳糖O抗原的生物合成所需的rfb基因簇之间的关系。

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The lipopolysaccharide O antigens of Klebsiella pneumoniae serotype O1 and Serratia marcescens serotype O16 both contain a repeating unit disaccharide of [-->3)-beta-D-Galf-(1-->3)-alpha-D-Galp-(1-->]; the resulting polymer is known as D-galactan I. In K. pneumoniae serotype O1, the genes responsible for the synthesis of D-galactan I are found in the rfb gene cluster (rfbKpO1). We report here the cloning and analysis of the rfb cluster from S. marcescens serotype O16 (rfbSmO16). This is the first rfb gene cluster examined for the genus Serratia. Synthesis of D-galactan I is an rfe-dependent process for both K. pneumoniae serotype O1 and S. marcescens serotype O16. Hybridization experiments with probes derived from each of the six rfbKpO1 genes indicate that the cloned rfbSmO16 cluster contains homologous genes arranged in the same order. However, the degree of homology at the nucleotide sequence level was sufficiently low that hybridization was detected only under low-stringency conditions. rfbABSmO16 genes were subcloned and shown to encode an ABC-2 (ATP-binding cassette) transporter which is functionally identical to the one encoded by the corresponding rfb genes from K. pneumoniae serotype O1. The amino acid sequences of the predicted RfbA and RfbB homologs showed identities of 75.7% (87.9% total similarity) and 78.0% (86.5% total similarity), respectively. The last gene of the rfbKpO1 cluster, rfbFKpO1, encodes a bifunctional galactosyltransferase which initiates the formation of D-galactan I. RfbFKpO1 and RfbFSmO16 are 57.6% identical (with 71.1% total similarity), and both show similarity with RfpB, the galactosyltransferase involved in the synthesis of Shigella dysenteriae type I O-polysaccharide. The G+C contents of the rfbAB genes from each organism are quite similar, and values are lower than those typical for the species. However, the G+C content of rfbFSmO16 (47.6%) was much higher than that of rfbFKpO1 (37.3%), despite the fact that the average for each species (52 to 60%) falls within the same range.
机译：肺炎克雷伯菌血清型O1和粘质沙雷氏菌血清型O16的脂多糖O抗原均含有[-> 3）-β-D-Galf-（1-> 3）-alpha-D-Galp-（1的重复单元二糖->];所得的聚合物称为D-半乳聚糖I.在肺炎克雷伯菌血清型O1中，在rfb基因簇（rfbKpO1）中发现了负责D-半乳聚糖I合成的基因。鼠链球菌血清型O16（rfbSmO16）的rfb簇的克隆和分析。这是检测沙雷氏菌属的第一个rfb基因簇。D-半乳聚糖I的合成是肺炎克雷伯菌血清型O1和S的rfe依赖过程。 。oces marcescens血清型O16。用来自六个rfbKpO1基因中每一个的探针进行的杂交实验表明，克隆的rfbSmO16簇包含以相同顺序排列的同源基因，但是，在核苷酸序列水平上的同源度很低，无法检测到杂交仅在低严格条件下离子。 rfbABSmO16基因被亚克隆并显示出编码一种ABC-2（ATP结合盒）转运蛋白，其功能与肺炎克雷伯菌血清型O1的相应rfb基因编码的转运蛋白功能相同。预测的RfbA和RfbB同源物的氨基酸序列分别显示出75.7％（87.9％的总相似性）和78.0％（86.5％的总相似性）。 rfbKpO1簇的最后一个基因rfbFKpO1编码了一个双功能的半乳糖基转移酶，该酶启动了D-半乳聚糖I的形成。RfbFKpO1和RfbFSmO16具有57.6％的同一性（总相似度为71.1％），并且都与半乳糖基转移酶RfpB相似。痢疾志贺氏菌I型O-多糖的合成。每个生物的rfbAB基因的G + C含量非常相似，其值低于该物种的典型值。但是，rfbFSmO16的G + C含量（47.6％）远远高于rfbFKpO1的G + C含量（37.3％），尽管每个物种的平均值（52％至60％）都在同一范围内。

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