Graduate Institute of Applied Science and Engineering, Fu Jen University, Taipei, Taiwan, Republic of China.
FEMS Microbiol Lett. 2010 Jan;302(2):138-43. doi: 10.1111/j.1574-6968.2009.01836.x. Epub 2009 Oct 28.
The phaC, phaP, phaR, and phaZ genes are involved in the synthesis, accumulation, and degradation of poly-beta-hydroxybutyrate (PHB). These genes encode the PHB synthase, phasin, regulatory protein, and PHB depolymerase, respectively, and are located in the same locus in the genome of Rhodobacter sphaeroides FJ1, a purple nonsulfur bacterium capable of producing PHB. We have previously found that the PhaR protein binds to the promoter regions of phaP, phaR, and phaZ and represses their expression. In this study, we determined that PhaR binds to an 11-bp palindromic sequence, 5'-CTGCN(3)GCAG-3', located at nucleotides -69 to -59 and -97 to -87 relative to the translation start site of phaP. Substitution of the three spacer nucleotides with any three or four nucleotides in this sequence had no effect on PhaR binding, but all other base deletions or substitutions in this sequence abolished its ability to bind PhaR both in vitro and in vivo. These results suggest that PhaR regulates the expression of phaP in R. sphaeroides FJ1.
phaC、phaP、phaR 和 phaZ 基因参与聚-β-羟基丁酸（PHB）的合成、积累和降解。这些基因分别编码 PHB 合酶、pha 蛋白、调节蛋白和 PHB 解聚酶，位于能够产生 PHB 的紫色非硫细菌红杆菌 FJ1 的基因组中的相同基因座上。我们之前发现 PhaR 蛋白结合到 phaP、phaR 和 phaZ 的启动子区域并抑制它们的表达。在这项研究中，我们确定 PhaR 结合到位于翻译起始位点 phaP 的-69 到-59 和-97 到-87 核苷酸处的 11 个碱基回文序列 5'-CTGCN(3)GCAG-3'。该序列中三个间隔核苷酸的任何三个或四个核苷酸的替换对 PhaR 结合没有影响，但该序列中所有其他碱基缺失或替换都使其在体外和体内均丧失与 PhaR 结合的能力。这些结果表明，PhaR 调节 R. sphaeroides FJ1 中 phaP 的表达。
