Chou Min-En, Chang Wen-Tuan, Chang Ya-Chieh, Yang Mei-Kwei
Graduate Institute of Applied Science and Engineering, Fu Jen University, Taipei, Taiwan, Republic of China.
Mol Genet Genomics. 2009 Jul;282(1):97-106. doi: 10.1007/s00438-009-0448-4. Epub 2009 Apr 29.
A cluster of genes encoding polyhydroxybutyrate (PHB) depolymerase (phaZ), PHB synthase (phaC), phasin (phaP), and the regulator protein (phaR) was previously identified in Rhodobacter sphaeroides FJ1 (R. sphaeroides FJ1). In this study, we investigated the role of the PhaR protein on the expression of the pha genes. Immunoblot analysis revealed that the expressions of phaP, phaZ and phaR genes in wild-type cells of R. sphaeroides FJ1 are repressed during the active growth phase, with the exception of phaC. A phaR deletion mutant of R. sphaeroides FJ1 was constructed, and the basal level of phaP and phaZ expression in this mutant was markedly increased. Electrophoretic mobility shift assays demonstrated that PhaR binds to the promoter region of phaP as well as those of phaR and phaZ. These results suggest that the PhaR protein is a repressor of phaP, phaR, and phaZ genes in R. sphaeroides FJ1.
先前在球形红杆菌FJ1（R. sphaeroides FJ1）中鉴定出了一组编码聚羟基丁酸酯（PHB）解聚酶（phaZ）、PHB合酶（phaC）、phasins（phaP）和调节蛋白（phaR）的基因。在本研究中，我们研究了PhaR蛋白对pha基因表达的作用。免疫印迹分析表明，在活跃生长阶段，R. sphaeroides FJ1野生型细胞中phaP、phaZ和phaR基因的表达受到抑制，但phaC除外。构建了R. sphaeroides FJ1的phaR缺失突变体，该突变体中phaP和phaZ表达的基础水平显著增加。电泳迁移率变动分析表明，PhaR与phaP以及phaR和phaZ的启动子区域结合。这些结果表明，PhaR蛋白是R. sphaeroides FJ1中phaP、phaR和phaZ基因的阻遏物。
