Walsh A G, Burrows L L, Lam J S
Canadian Bacterial Diseases Network, Department of Microbiology, University of Guelph, Ont., Canada.
FEMS Microbiol Lett. 1999 Apr 1;173(1):27-33. doi: 10.1111/j.1574-6968.1999.tb13480.x.
A Pseudomonas aeruginosa serotype O5 (PAO1) genomic DNA fragment that was able to complement a temperature-sensitive mutation in the 3-deoxy-D-manno-octulosonic acid (Kdo) 8-P synthase gene (kdsA) of Salmonella enterica serovar typhimurium was cloned. Nucleotide sequence analysis revealed the presence of a potential operon with the gene order pyrG, kdsA, eno. PyrG catalyzes the synthesis of the nucleotide cytidine triphosphate, while Eno catalyzes the formation of phosphoenolpyruvate from phosphoglycerate during glycolysis. Phosphoenolpyruvate is one of the substrates for Kdo-8-P biosynthesis by KdsA and cytidine triphosphate is the nucleotide used to activate Kdo prior to its transfer to lipid A. pyrG and eno are important for many metabolic pathways and it is interesting to find them linked to kdsA. A sigma 70-like promoter was found upstream of pyrG and evidence was provided to show that this promoter was responsible for the initiation of transcription of the genes in this operon. These genes mapped to 28.2-29.9 min on the 75-min PAO1 chromosome, unlinked to other lipopolysaccharide biosynthetic gene clusters.
克隆了一个铜绿假单胞菌O5血清型（PAO1）的基因组DNA片段，该片段能够互补鼠伤寒沙门氏菌3-脱氧-D-甘露糖辛酮酸（Kdo）8-磷酸合酶基因（kdsA）中的温度敏感突变。核苷酸序列分析显示存在一个潜在的操纵子，其基因顺序为pyrG、kdsA、eno。PyrG催化三磷酸胞苷的合成，而Eno在糖酵解过程中催化磷酸甘油酸形成磷酸烯醇丙酮酸。磷酸烯醇丙酮酸是KdsA合成Kdo-8-磷酸的底物之一，三磷酸胞苷是Kdo在转移至脂质A之前用于激活它的核苷酸。pyrG和eno对许多代谢途径都很重要，发现它们与kdsA相连很有意思。在pyrG上游发现了一个类似σ70的启动子，并提供了证据表明该启动子负责此操纵子中基因转录的起始。这些基因位于75分钟的PAO1染色体上的28.2 - 29.9分钟处，与其他脂多糖生物合成基因簇不连锁。
