Tsukamoto N, Fujii I, Ebizuka Y, Sankawa U
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
J Bacteriol. 1994 Apr;176(8):2473-5. doi: 10.1128/jb.176.8.2473-2475.1994.
A 3.4-kb BamHI fragment that is assumed to be a part of the aklavinone biosynthetic gene cluster of Streptomyces galilaeus 3AR-33 and contains the genes required for the early stage of polyketide biosynthesis was sequenced. The nucleotide sequence of the region that hybridizes to the actIII probe reveals the presence of a gene, aknA, whose deduced protein product is very similar to the ActIII protein and other known oxidoreductases. The predicted AknA protein is believed to be responsible for catalyzing the reduction of the keto group at the ninth carbon from the carboxyl terminus of the assembled polyketide to the corresponding secondary alcohol. The predicted AknA protein has a calculated molecular mass of 27,197 Da (261 amino acids) and the highly conserved sequence Gly-Xaa-Gly-Xaa-Xaa-Ala commonly seen in oxidoreductases. Cloning and sequence analysis of the aknA region of the 2-hydroxyaklavinone-producing strain S. galilaeus ANR-58 identified an alteration in the gene, confirming that the aknA gene is essential for aklavinone biosynthesis.
对一个3.4kb的BamHI片段进行了测序，该片段被认为是加利利链霉菌3AR - 33阿克拉维酮生物合成基因簇的一部分，包含聚酮生物合成早期所需的基因。与actIII探针杂交区域的核苷酸序列显示存在一个基因aknA，其推导的蛋白质产物与ActIII蛋白和其他已知氧化还原酶非常相似。预测的AknA蛋白被认为负责催化组装好的聚酮从羧基末端起第九个碳上的酮基还原为相应的仲醇。预测的AknA蛋白计算分子量为27,197Da（261个氨基酸），具有氧化还原酶中常见的高度保守序列Gly - Xaa - Gly - Xaa - Xaa - Ala。对产2 - 羟基阿克拉维酮的菌株加利利链霉菌ANR - 58的aknA区域进行克隆和序列分析，发现该基因发生了改变，证实aknA基因对阿克拉维酮生物合成至关重要。
