Tangney M, Mitchell W J
Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh, UK.
J Mol Microbiol Biotechnol. 2000 Jan;2(1):71-80.
The utilization of sucrose by Clostridium acetobutylicum ATCC 824 was investigated. Sucrose was found to be transported via a phosphoenol-pyruvate (PEP)-dependent phosphotransferase system (PTS) and a metabolic pathway identical to that previously identified in C. beijerinckii, was established. The genes encoding the proteins of this pathway were identified from the C. acetobutylicum genome sequence, in the order scrAKB encoding Enzyme II of the sucrose PTS, fructokinase and sucrose 6-phosphate hydrolase respectively. While the pathway for sucrose metabolism is conserved between C. acetobutylicum and C. beijerinckii, the operons show considerable differences in organization and regulatory elements. The C. acetobutylicum scr operon contains the elements of an antiterminator-mediated regulation mechanism, typical of the BgIG family of regulators. The scrT gene, located upstream of scrA encodes an antiterminator that is preceded by a transcription terminator, which is overlapped by a classical ribonucleic antiterminator (RAT) sequence. We also propose the existence of a new variant RAT-like sequence which overlaps a terminator between scrT and the downstream structural genes.
对丙酮丁醇梭菌ATCC 824利用蔗糖的情况进行了研究。发现蔗糖通过磷酸烯醇丙酮酸（PEP）依赖性磷酸转移酶系统（PTS）进行转运，并建立了一条与先前在拜氏梭菌中鉴定出的代谢途径相同的代谢途径。从丙酮丁醇梭菌基因组序列中鉴定出了编码该途径蛋白质的基因，顺序为分别编码蔗糖PTS的酶II、果糖激酶和蔗糖6-磷酸水解酶的scrAKB。虽然丙酮丁醇梭菌和拜氏梭菌之间蔗糖代谢途径是保守的，但操纵子在组织和调控元件方面存在相当大的差异。丙酮丁醇梭菌的scr操纵子包含抗终止子介导的调控机制元件，这是BgIG家族调控因子的典型特征。位于scrA上游的scrT基因编码一个抗终止子，其前面有一个转录终止子，该终止子与一个经典的核糖核酸抗终止子（RAT）序列重叠。我们还提出存在一种新的变体RAT样序列，它与scrT和下游结构基因之间的一个终止子重叠。
