Zheng Zhong, Li Ming, Xue Xiao-Jing, Tian Hong-Lei, Li Zhi, Chen Guo-Qiang
MOE Laboratory of Protein Science, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, China.
Appl Microbiol Biotechnol. 2006 Oct;72(5):896-905. doi: 10.1007/s00253-006-0371-0. Epub 2006 May 4.
Polyhydroxyalkanoate (PHA) synthase is the central enzyme involved in the biosynthesis of PHA, a family of bacterial biodegradable polyesters. Due to its high variability, the N-terminal fragment of this enzyme was previously considered as unnecessary for a functionally active enzyme. In this study, polyhydroxybutyrate synthase from Ralstonia eutropha (PhbC(Re)) with a deletion on N-terminal 88 amino acid residues showed a significant reduced activity, as reflected by only 1.5% PHB accumulation compared with the wild type which produced 58.4% PHB of the cell dry weight. Whilst several site-specific mutagenesis results revealed the amphiphilic alpha-helix assembled by the amino acid region, D70-E88 played an important role in both maintaining the PHB synthase activity and regulating molecular weight and polydispersity of accumulated PHB homopolymer.
聚羟基链烷酸酯（PHA）合酶是参与PHA生物合成的核心酶，PHA是一类细菌可生物降解的聚酯。由于其高度变异性，该酶的N端片段以前被认为对于功能活性酶来说是不必要的。在本研究中，真养产碱杆菌（Ralstonia eutropha）的聚羟基丁酸酯合酶（PhbC(Re)）N端88个氨基酸残基缺失后活性显著降低，这表现为与产生细胞干重58.4% PHB的野生型相比，PHB积累量仅为1.5%。虽然几个位点特异性诱变结果揭示了由氨基酸区域D70 - E88组装的两亲性α-螺旋在维持PHB合酶活性以及调节积累的PHB均聚物的分子量和多分散性方面都发挥了重要作用。
