Molecular analysis of the Pseudomonas aeruginosa regulatory genes ptxR and ptxS
Molecular analysis of the Pseudomonas aeruginosa regulatory genes ptxR and ptxS
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DOI：
10.1139/cjm-47-9-820
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发表时间：
2001-09-01
影响因子：
2.8
通讯作者：
Hamood, AN
中科院分区：
文献类型：
--
作者：
Colmer, JA;Hamood, AN
我们先前已经描述了两个铜绿假单胞菌基因，ptxR，其增强toxA和pvc（绿脓菌荧光素发色操纵子）表达，以及ptxS，其是铜绿假单胞菌利用2-酮葡糖酸的kgu操纵子的第一个基因。ptxS干扰ptxR对toxA表达的作用。在这项研究中，我们利用DNA杂交实验，以确定ptxR和ptxS同源序列在几个革兰氏阴性菌的存在。仅在铜绿假单胞菌菌株中检测到ptxR同源序列，而在铜绿假单胞菌、恶臭假单胞菌和荧光假单胞菌中检测到ptxS同源序列。使用北方印迹杂交实验和ptxS-lacZ融合质粒，我们已经表明铜绿假单胞菌ptxR和ptxS在恶臭假单胞菌和荧光假单胞菌中表达。另外的北方印迹杂交实验证实ptxS在不携带质粒的恶臭假单胞菌和荧光假单胞菌菌株中转录。在这些菌株中的PtxS同源物的存在下，通过DNA凝胶移位实验进行了检查。当铜绿假单胞菌、恶臭假单胞菌和荧光假单胞菌的裂解物与ptxS操作位点作为探针孵育时，检测到特异性凝胶位移条带。在恶臭假单胞菌和荧光假单胞菌中均检测到kgu-杂交序列。这些结果表明：（i）ptxR存在于铜绿假单胞菌中，而ptxS存在于铜绿假单胞菌、恶臭假单胞菌和荧光假单胞菌中;（ii）ptxR和ptxS均在恶臭假单胞菌和荧光假单胞菌中表达;（iii）PtxS同源物可能存在于恶臭假单胞菌和荧光假单胞菌中。
We have previously described two Pseudomonas aeruginosa genes, ptxR, which enhances toxA and pvc ( the pyoverdine chromophore operon) expression, and ptxS, the first gene of the kgu operon for the utilization of 2-ketogluconate by P. aeruginosa. ptxS interferes with the effect of ptxR on toxA expression. In this study, we have utilized DNA hybridization experiments to determine the presence of ptxR and ptxS homologous sequences in several gram-negative bacteria. ptxR homologous sequences were detected in P. aeruginosa strains only, while ptxS homologous sequences were detected in P. aeruginosa, Pseudomonas putida, and Pseudomonas fluorescens. Using Northern blot hybridization experiments and a ptxS-lacZ fusion plasmid, we have shown that P. aeruginosa ptxR and ptxS are expressed in P. putida and P. fluorescens. Additional Northern blot hybridization experiments confirmed that ptxS is transcribed in P. putida and P. fluorescens strains that carried no plasmid. The presence of a PtxS homologue in these strains was examined by DNA-gel shift experiments. Specific gel shift bands were detected when the lysates of P. aeruginosa, P. putida, and P. fluorescens were incubated with the ptxS operator site as probe. kgu-hybridizing sequences were detected in P. putida and P. fluorescens. These results suggest that (i) ptxR is present in P. aeruginosa, while ptxS is present in P. aeruginosa, P. putida, and P. fluorescens; (ii) both ptxR and ptxS are expressed in P. putida and P. fluorescens; and (iii) a PtxS homologue may exist in P. putida and P. fluorescens.