Beil S, Timmis K N, Pieper D H
Division of Microbiology, GBF-National Research Centre for Biotechnology, Braunschweig, Germany.
J Bacteriol. 1999 Jan;181(1):341-6. doi: 10.1128/JB.181.1.341-346.1999.
The TecA broad-spectrum chlorobenzene dioxygenase of Burkholderia sp. strain PS12 catalyzes the first step in the mineralization of 1,2,4, 5-tetrachlorobenzene. The catabolic genes were localized on a small plasmid that belongs to the IncPbeta incompatibility group. PCR analysis of the genetic environment of the tec genes indicated high similarity to the transposon-organized catabolic tcb chlorobenzene degradation genes of Pseudomonas sp. strain P51. Sequence analysis of the regions flanking the tecA genes revealed an upstream open reading frame (ORF) with high similarity to the todF 2-hydroxy-6-oxo-2,4-heptadienoate hydrolase gene of Pseudomonas putida F1 and a discontinuous downstream ORF showing high similarity to the todE catechol 2,3-dioxygenase gene of strain F1. Both homologues in strain P51 exist only as deletion remnants. We suggest that different genetic events thus led to inactivation of the perturbing meta-cleavage enzymes in strains P51 and PS12 during the evolution of efficient chlorobenzene degradation pathways. Biochemical characterization of TodF-like protein TlpF and a genetically refunctionalized TodE-like protein, TlpE, produced in Escherichia coli provided data consistent with the proposed relationships.
伯克霍尔德氏菌属PS12菌株的TecA广谱氯苯双加氧酶催化1,2,4,5-四氯苯矿化的第一步。分解代谢基因定位于一个属于IncPbeta不相容群的小质粒上。对tec基因遗传环境的PCR分析表明，其与假单胞菌属P51菌株转座子组织的分解代谢tcb氯苯降解基因高度相似。tecA基因侧翼区域的序列分析揭示了一个上游开放阅读框（ORF），它与恶臭假单胞菌F1的todF 2-羟基-6-氧代-2,4-庚二烯酸水解酶基因高度相似，以及一个不连续的下游ORF，它与菌株F1的todE儿茶酚2,3-双加氧酶基因高度相似。P51菌株中的这两个同源物仅作为缺失残余存在。我们认为，在高效氯苯降解途径的进化过程中，不同的遗传事件导致了P51和PS12菌株中干扰间位裂解酶的失活。在大肠杆菌中产生的TodF样蛋白TlpF和基因功能重新恢复的TodE样蛋白TlpE的生化特性提供的数据与所提出的关系一致。
