Rogers J D, Scannapieco F A
Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA.
J Bacteriol. 2001 Jun;183(11):3521-5. doi: 10.1128/JB.183.11.3521-3525.2001.
The amylase-binding protein A (AbpA) of Streptococcus gordonii was found to be undetectable in supernatants of mid-log-phase cultures containing >1% glucose but abundant in supernatants of cultures made with brain heart infusion (BHI), which contains 0.2% glucose. A 10-fold decrease in the level of abpA mRNA in S. gordonii cells cultured in BHI was noted after the addition of glucose to 1%. Analysis of the abpA sequence revealed a potential catabolite responsive element CRE 153 bp downstream of the putative translational start site. A catabolite control protein A gene (ccpA) homolog from S. gordonii, designated regG, was cloned. A regG mutant strain demonstrated moderately less repression of abpA transcription in the presence of 1% glucose. Diauxic growth with glucose and lactose was not affected in the RegG mutant compared to the wild-type parental strain. These results suggest that while RegG plays a role in abpA expression, other mechanisms of catabolite repression are present.
研究发现，戈登氏链球菌的淀粉酶结合蛋白A（AbpA）在用含1%以上葡萄糖的对数中期培养基培养的上清液中无法检测到，但在用含0.2%葡萄糖的脑心浸液（BHI）培养的上清液中含量丰富。在BHI中培养的戈登氏链球菌细胞中，当葡萄糖添加量达到1%后，abpA mRNA水平下降了10倍。对abpA序列的分析显示，在假定的翻译起始位点下游153 bp处存在一个潜在的分解代谢物反应元件（CRE）。从戈登氏链球菌中克隆出一个分解代谢物控制蛋白A基因（ccpA）的同源物，命名为regG。与野生型亲本菌株相比，regG突变株在1%葡萄糖存在的情况下对abpA转录的抑制作用略有减弱。与野生型亲本菌株相比，RegG突变株在利用葡萄糖和乳糖进行的二次生长不受影响。这些结果表明，虽然RegG在abpA表达中发挥作用，但还存在其他分解代谢物阻遏机制。
