Bioresource Research Unit, National Center for Genetic Engineering and Biotechnology, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand.
Fungal Genet Biol. 2013 Jan;50:55-62. doi: 10.1016/j.fgb.2012.10.005. Epub 2012 Nov 19.
Fungi from the genus Xylaria produce a wide range of polyketides with diverse structures, which provide important sources for pharmaceutical agents. At least seven polyketide synthase (PKS) genes, including pksmt, were found in Xylaria sp. BCC 1067. The multifunctional enzyme pksmt contains the following catalytic motifs: β-ketosynthase (KS), acyltransferase (AT), dehydratase (DH), methyltransferase (MT), enoylreductase (ER), ketoreductase (KR), and acyl carrier region (ACP). The presence of multiple domains indicated that pksmt was an iterative type I highly-reduced-type PKS gene. To identify the gene function, pksmt was fused with a gene encoding green fluorescent protein (GFP) and introduced into a surrogate host, Aspergillus oryzae, and expressed under the control of a constitutive gpdA promoter. In the transformant, the pksmt gene was functionally expressed and translated as detected by a green fluorescence signal. This transformant produced two new 2-pyrone compounds, 4-(hydroxymethyl)-5,6-dihydro-pyran-2-one and 5-hydroxy-4-methyl-5,6-dihydro-pyran-2-one, as well as a previously identified 4-methyl-5,6-dihydro-pyran-2-one. Our results suggested that pksmt from Xylaria sp. BCC 1067 represents a family of fungal PKSs that can synthesize 2-pyrone-containing compounds.
木层孔菌属真菌产生具有多种结构的广泛的聚酮化合物，为药物提供了重要来源。在木层孔菌 BCC 1067 中发现了至少七个聚酮合酶（PKS）基因，包括 pksmt。多功能酶 pksmt 包含以下催化基序：β-酮基合酶（KS）、酰基转移酶（AT）、脱水酶（DH）、甲基转移酶（MT）、烯酰还原酶（ER）、酮还原酶（KR）和酰基载体区域（ACP）。多个结构域的存在表明 pksmt 是一种迭代型 I 型高度还原型 PKS 基因。为了鉴定基因功能，将 pksmt 与编码绿色荧光蛋白（GFP）的基因融合，并引入替代宿主 Aspergillus oryzae 中，在组成型 gpdA 启动子的控制下表达。在转化体中，通过绿色荧光信号检测到 pksmt 基因的功能性表达和翻译。该转化体产生了两种新的 2-吡喃酮化合物，4-（羟甲基）-5,6-二氢-2-吡喃酮和 5-羟基-4-甲基-5,6-二氢-2-吡喃酮，以及先前鉴定的 4-甲基-5,6-二氢-2-吡喃酮。我们的结果表明，木层孔菌 BCC 1067 的 pksmt 代表了一类能够合成含 2-吡喃酮化合物的真菌 PKS。
