Study on the transport of the Opolysaccharide in Escherichia

Research Project

Project/Area Number	12670253
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Bacteriology (including Mycology)
Research Institution	Nagoya University
Principal Investigator	KIDO Nobuo Unit Biosystems, Sch. Info&Sci, Associate, Professor, 情報文化学部, 助教授 (80161511)
Project Period (FY)	2000 – 2001
Project Status	Completed (Fiscal Year 2001)
Budget Amount *help	¥3,200,000 (Direct Cost: ¥3,200,000) Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
Keywords	eudotoxin / lipopolysaccharide / O polysaccharide / LPS / 莢膜多糖 / 大腸菌 / 細菌表層多糖 / 膜輸送
Research Abstract	O polysaccharides of Gram-negative bacteria are structurally polymorphic, and consequently, they are utilized as the O-antigen for serological typing. The O polysaccharide is part of lipopolysaccharides (LPS) and covalently binds to lipid A through the core-oligosaccharide portion. The wb* gene cluster is responsible for the O polysaccharide synthesis.The wb* cluster of Escherichia coll O9a strain F719 is constituted of eight genes, two for GDP-mannose synthesis, two for the putative ABC-transporter, three for mannosyltransferases, and one whose function is unknown. The gene, wbdD, was investigated its function using mutated plasmid and the complementation test. Tn1000 inserted plasmid synthesized the O9a polysaccharides but they did not transport to the cell surface instead found in cell cytoplasm. Electron microscopic analysis using a monoclonal antibody against the O9a polysaccharide confirmed this distribution of the polysaccharides. Cloned wbdD gene complemented the mutation, however, when the cloned gene was over expressed under the control of the lac promoter, the length of the O polysaccharides synthesized became shorter. Based on these results, the possibility was shown that there might be another transport system in addition to the ABC-transport system revealed by the genes in the cluster. Moreover, the change in the polysaccharide length suggested that the novel transport system might be correlated with the timing that the synthesized O polysaccharides are transferred to the core-oligosaccharide of LPS. More detailed analyzes would be necessary to confirm the hypothesis.