Asanuma Narito, Kanada Kazuhiro, Hino Tsuneo
Department of Life Science, College of Agriculture, Meiji University, Higashimita, Tama-ku, 1-1-1 Kawasaki 214-8571, Japan.
Anaerobe. 2008 Oct;14(4):237-41. doi: 10.1016/j.anaerobe.2008.05.004. Epub 2008 May 22.
Molecular properties of pyruvate kinase (PYK) and phosphofructokinase (PFK) in Streptococcus bovis and transcriptional control of the two enzymes were examined. Sequence analysis indicated that the PYK gene (pyk) clusters with the PFK gene (pfk) and several other genes. It was demonstrated that the pyk and pfk are cotranscribed and their transcription appeared to be regulated at the transcriptional level in response to the sugars supplied. The intracellular pyk-mRNA level was lower in a catabolite control protein A (CcpA)-disrupted mutant than in its parent strain, and a binding site of CcpA was found in the upstream region of pfk. These results suggest that pfk-pyk transcription is enhanced by CcpA. A recombinant pyk-overexpressing strain showed approximately five-fold higher PYK activity, but it did not affect the growth rate or formate-to-lactate ratio significantly, suggesting that the flux in the glycolytic pathway is not altered by an increase in PYK activity.
对牛链球菌中丙酮酸激酶（PYK）和磷酸果糖激酶（PFK）的分子特性以及这两种酶的转录调控进行了研究。序列分析表明，PYK基因（pyk）与PFK基因（pfk）以及其他几个基因聚集在一起。结果表明，pyk和pfk是共转录的，并且它们的转录似乎在转录水平上受到所供应糖类的调控。在分解代谢物控制蛋白A（CcpA）缺失的突变体中，细胞内pyk - mRNA水平低于其亲本菌株，并且在pfk的上游区域发现了CcpA的结合位点。这些结果表明，CcpA可增强pfk - pyk的转录。一个重组的pyk过表达菌株显示PYK活性大约高五倍，但它对生长速率或甲酸与乳酸的比例没有显著影响，这表明糖酵解途径中的通量不会因PYK活性的增加而改变。
