A biosynthetic gene cluster for a secreted cellobiose lipid with antifungal activity from Ustilago maydis
A biosynthetic gene cluster for a secreted cellobiose lipid with antifungal activity from Ustilago maydis
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DOI：
10.1111/j.1365-2958.2007.05941.x
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发表时间：
2007-10-01
影响因子：
3.6
通讯作者：
Boelker, Michael
中科院分区：
文献类型：
--
作者：
Teichmann, Beate;Linne, Uwe;Boelker, Michael
玉米黑粉菌（Ustilago maydis）是一种重要的植物病原真菌，能分泌大量的糖脂表面活性剂--黑粉菌酸（Ustilagoacid，UA）。UA由15，16-二羟基棕榈酸或2，15，16-三羟基棕榈酸组成，其在其末端羟基处与纤维二糖O-糖苷连接。此外，纤维二糖部分被乙酰化并被短链羟基脂肪酸酰化。我们已经确定了一个58 kb的跨越基因簇，其中包含12个开放阅读框编码大多数，如果不是全部，UA生物合成所需的酶。使用遗传和质谱分析的组合，我们能够将功能角色分配给基因簇编码的三种蛋白质。这使我们能够提出UA的生物合成途径。Ahd 1蛋白属于非血红素二铁还原酶家族，是棕榈酸α-羟基化所必需的。两种P450单加氧酶Cyp 1和Cyp 2催化棕榈酸的末端和亚末端羟基化。我们可以证明，番茄叶片感染的植物病原真菌灰葡萄孢菌是防止共同接种野生型U。玉米孢子虫联合UA生物合成缺陷的玉米突变体不能抑制B。灰霉病菌感染表明UA分泌是拮抗活性的关键。
The phytopathogenic basidiomycetous fungus Ustilago maydis secretes large amounts of the glycolipid biosurfactant ustilagic acid (UA). UA consists of 15,16-dihydroxypalmitic or 2,15,16-trihydroxypalmitic acid, which is O-glycosidically linked to cellobiose at its terminal hydroxyl group. In addition, the cellobiose moiety is acetylated and acylated with a short-chain hydroxy fatty acid. We have identified a 58 kb spanning gene cluster that contains 12 open reading frames coding for most, if not all, enzymes needed for UA biosynthesis. Using a combination of genetic and mass spectrometric analysis we were able to assign functional roles to three of the proteins encoded by the gene cluster. This allowed us to propose a biosynthesis route for UA. The Ahd1 protein belongs to the family of non-haem diiron reductases and is required for alpha-hydroxylation of palmitic acid. Two P450 monooxygenases, Cyp1 and Cyp2, catalyse terminal and subterminal hydroxylation of palmitic acid. We could demonstrate that infection of tomato leaves by the plant pathogenic fungus Botrytis cinerea is prevented by co-inoculation with wild-type U. maydis sporidia. U. maydis mutants defective in UA biosynthesis were unable to inhibit B. cinerea infection indicating that UA secretion is critical for antagonistic activity.