O'Leary Niall D, O'Connor Kevin E, Duetz Wouter, Dobson Alan D W
Microbiology Department, National University of Ireland, Cork, Ireland1.
Department of Industrial Microbiology, National University of Ireland, Dublin, Ireland2.
Microbiology (Reading). 2001 Apr;147(Pt 4):973-979. doi: 10.1099/00221287-147-4-973.
The styrene degradative pathway in Pseudmonas putida CA-3 has previously been shown to be divided into an upper pathway involving the conversion of styrene to phenylacetic acid and a lower pathway for the subsequent degradation of phenylacetic acid. It is reported here that expression of the regulatory genes styS and styR is essential for transcription of the upper pathway, but not for degradation of the lower pathway inducer, phenylacetic acid. The presence of phenylacetic acid in the growth medium completely repressed the upper pathway enzymes even in the presence of styrene, the upper pathway inducer. This repression is mediated at the transcription level by preventing expression of the styS and styR regulatory genes. Finally, an examination was made of the various stages of the diauxic growth curve obtained when P. putida CA-3 was grown on styrene together with an additional carbon source and it is reported that catabolite repression may involve a different mechanism to transcriptional repression by an additional carbon source.
恶臭假单胞菌CA-3中的苯乙烯降解途径先前已被证明分为一个上途径，涉及苯乙烯转化为苯乙酸，以及一个下途径，用于随后苯乙酸的降解。本文报道，调控基因styS和styR的表达对于上途径的转录至关重要，但对于下途径诱导物苯乙酸的降解并非必需。即使在上途径诱导物苯乙烯存在的情况下，生长培养基中苯乙酸的存在也会完全抑制上途径的酶。这种抑制是通过阻止styS和styR调控基因的表达在转录水平上介导的。最后，对恶臭假单胞菌CA-3在苯乙烯与额外碳源一起生长时获得的双相生长曲线的各个阶段进行了研究，据报道，分解代谢物阻遏可能涉及与额外碳源的转录阻遏不同的机制。
