p-Cymene catabolic pathway in Pseudomonas putida F1: Cloning and characterization of DNA encoding conversion of p-cymene to p-cumate
p-Cymene catabolic pathway in Pseudomonas putida F1: Cloning and characterization of DNA encoding conversion of p-cymene to p-cumate
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DOI：
10.1128/jb.179.10.3171-3180.1997
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发表时间：
1997-05-01
影响因子：
3.2
通讯作者：
Eaton, RW
中科院分区：
文献类型：
--
作者：
Eaton, RW
恶臭假单胞菌F1通过11步途径利用对异丙基甲苯（对异丙基甲苯），通过对异丙基苯甲酸酯（对异丙基苯甲酸酯）生成异丁酸酯、丙酮酸酯和乙酰辅酶A。cym操纵子编码对伞花烃转化为对枯酸，它位于cmt操纵子的上游，cmt操纵子编码对枯酸的进一步催化，而cmt操纵子又位于fod的上游携带cym操纵子的11，236-bp DNA片段和完成2，已确定并讨论了分离cmf和tod操纵子的673 bp DNA片段。cymAa和cymAb分别编码对伞花烃单加氧酶的两个组分，即羟化酶和还原酶，cymB编码对枯醇脱氢酶，cymC编码对枯醛脱氢酶，cymC编码对枯醇脱氢酶，cymB编码对枯醛脱氢酶，cymC编码对枯醇脱氢酶，cymB编码对枯醛脱氢酶，cymC编码对枯醇脱氢酶，cymC编码对枯醛脱氢酶，cymB编码对枯醇脱氢酶，cymC编码对枯醛脱氢酶，cymB编码对枯醇脱氢酶，cymC编码对枯醛脱氢酶。cymD编码与其他芳烃分解代谢操纵子的基因产物相关的推定外膜蛋白，但在对伞花烃分解代谢中具有未知功能;并且cymE编码乙酰辅酶A合成酶，其在该途径中的作用也是未知的。cymR位于cymD的上游。通过使用携带cymR操纵子或cmt操纵子的操纵子-启动子区的重组细菌，在cymR存在或不存在的情况下，在编码容易测定的酶的基因上游，证明了cymR编码控制cymR和cmt操纵子表达的阻遏物，并且可被对-cumate诱导，但不被对-cymene诱导，短（小于350 bp）的同源DNA片段，位于cymR的上游和之间的cmt和tod操纵子可能参与重组事件，导致目前的安排cym-cmt，和fod基因在P，putida F1。
Pseudomonas putida F1 utilizes p-cymene (p-isopropyltoluene) by an 11-step pathway through p-cumate (p-isopropylbenzoate) to isobutyrate, pyruvate, and acetyl coenzyme A. The cym operon, encoding the conversion of p-cymene to p-cumate, is located just upstream of the cmt operon, which encodes the further catabolism of p-cumate and is located, in turn, upstream of the fod (toluene catabolism) operon in P. putida F1, The sequences of an 11,236-bp DNA segment carrying the cym operon and a 915-bp DNA segment completing the sequence of the 2,673-bp DNA segment separating the cmf and tod operons have been determined and are discussed here. The cym operon contains six genes in the order cymBCAaAbDE, The gene products have been identified both by functional assays and by comparing deduced amino acid sequences to published sequences, Thus, cymAa and cymAb encode the two components of p-cymene monooxygenase, a hydroxylase and a reductase, respectively; cymB encodes p-cumic alcohol dehydrogenase; cymC encodes p-cumic aldehyde dehydrogenase; cymD encodes a putative outer membrane protein related to gene products of other aromatic hydrocarbon catabolic operons, but having an unknown function in p-cymene catabolism; and cymE encodes an acetyl coenzyme A synthetase whose role in this pathway is also unknown, Upstream of the cym operon is a regulatory gene, cymR. By using recombinant bacteria carrying either the operator-promoter region of the cym operon or the cmt operon upstream of genes encoding readily assayed enzymes, in the presence or absence of cymR, it was demonstrated that cymR encodes a repressor which controls expression of both the cym and cmt operons and is inducible by p-cumate but not p-cymene, Short (less than 350 bp) homologous DNA segments that are located upstream of cymR and between the cmt and tod operons may have been involved in recombination events that led to the current arrangement of cym, cmt, and fod genes in P, putida F1.