A plant type III polyketide synthase that produces pentaketide chromone
A plant type III polyketide synthase that produces pentaketide chromone
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DOI：
10.1021/ja0431206
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发表时间：
2005-02-09
影响因子：
15
通讯作者：
Noguchi, H
中科院分区：
文献类型：
--
作者：
Abe, I;Utsumi, Y;Noguchi, H
从芦荟（Aloarborescens）中克隆了一种新的植物特异性III型聚酮合酶（PKS），该酶催化5个丙二酰辅酶A分子形成5，7-二羟基-2-甲基色酮（pentaketide chromone）。定点突变显示Met 207（对应于CHS中的Thr 197）决定了聚酮化合物链的长度和酶的产物特异性;值得注意的是，用Gly替换一个氨基酸残基Met 207，产生了一种突变酶，它能有效地产生芳香族八肽，SEK 4和SEK 4 b，它们是放线菌紫素最小PKS的产物（来自天蓝色链霉菌），来自八个丙二酰辅酶A分子。这为CHS超家族III型PKS酶的催化功能和特异性提供了新的见解。
A novel plant-specific type III polyketide synthase (PKS) that catalyzes formation of a pentaketide chromone, 5,7-dihydroxy-2-methylchromone, from five molecules of malonyl-CoA, was cloned and sequenced from aloe (Aloearborescens). Site-directed mutagenesis revealed that Met207 (corresponding to Thr197 in CHS) determines the polyketide chain length and the product specificity of the enzyme; remarkably, replacement of a single amino acid residue, Met207, with Gly yielded a mutant enzyme that efficiently produces aromatic octaketides, SEK4 and SEK4b, the products of the minimal PKS for actinorhodin (actfromStreptomyces coelicolor), from eight molecules of malonyl-CoA. This provided new insights into the catalytic functions and specificities of the CHS-superfamily type III PKS enzymes.