Genetic Analyzes of Biosynthesis Mechanism of Capsular Polysaccharide as a Pathogenic Determinant.

近两年来，我们一直在研究细菌荚膜多糖（CPS）的生物合成机制，CPS被认为是细菌致病的决定因素之一。本课题将参与K_2CPS生物合成的肺炎克雷伯菌Chedid（K_2：O_1）的cps基因簇亚克隆到M_13、mp_（18）和mp_（19）中，并测定了其全长约24kb的核苷酸序列。本研究为克雷伯氏菌cps簇的结构及其调控提供了许多重要的新发现和信息。在测序区域至少鉴定出19个开放阅读框架（ORF），并发现了几个与cpsG、cpsB、gnd和galF相似的基因。与血清型K2 CPS的合成有关的区域位于测序区域的中心部分，并且表明该区域中的基因的表达通过位于ORF 3的上游区域中的基因的功能即使在稳定期仍然继续。然而，一些基因的功能仍然是未知的，因此，我们计划在下一个研究阶段继续分析它们在CPS生物合成中的作用。

In these two years, we have been studying on the biosynthesis mechanisms of bacterial capsular polysaccharide (CPS) which has been regarded as one of the bacterial pathogenic determinants. The cps gene cluster of K pneumoniae Chedid (K2 : O1), which is involved in the biosynthesis of serotype K2 CPS,has been subcloned into M13 phages, mp 18 and mp 19, and the entire nucleotide sequence, about 24-kb, was determined in the term of this project. This investigation provided us many important new findings and information about the structure of the Klebsiella cps cluster and its regulation. At least 19 putative open reading frames (ORFs) were identified in the sequenced area, and several genes similar to the cpsG,cpsB,gnd, and galF were found in this region. The region implicated in the synthesis of serotype K2 CPS was localized in the central portion of the sequenced area, and it was suggested that the expression of genes in this region still continue even in the stationary phase by the function of a gene locating in the upstream region of the ORF3. However, the functions of several genes are still unknown, therefore we are planning to continue the analyzes of their roles in the biosynthesis of CPS in the next term of investigation.