Structural and functional characterization of TRI3 trichothecene 15-O-acetyltransferase from Fusarium sporotrichioides
Structural and functional characterization of TRI3 trichothecene 15-O-acetyltransferase from Fusarium sporotrichioides
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DOI：
10.1002/pro.80
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发表时间：
2009-04-01
期刊：
影响因子：
8
通讯作者：
Rayment, Ivan
中科院分区：
文献类型：
--
作者：
Garvey, Graeme S.;McCormick, Susan P.;Rayment, Ivan
镰刀菌头疫病是谷类作物的一种毁灭性疾病，其在世界范围内的发病率正在上升，目前尚无令人满意的方法来防治这种病原体或其相关毒素。毛霉烯真菌毒素种类繁多，它们都含有12,13-环氧毛霉烯骨架，但它们的取代位置不同。事实上，在许多镰刀菌物种中，毒素谱存在相当大的差异，这归因于生物合成酶的存在或不存在及其相对活性的差异。本文讨论了毛霉烯分子C15位置乙酰化差异的来源。在这里，我们研究了从孢子毛线虫中分离的15- o -毛霉烯乙酰转移酶TRI3的体外结构和生化特性，以及产生脱氧雪腐镰刀菌醇（DON）的F. graminearum菌株的Delta TRI3突变体的“体内”特性。动力学分析表明，TRI3对天然底物15-decalonectrin是一种有效的酶，但对DON或nivalinol无活性。TRI3与15-decalonectrin络合的结构解释了这种特异性，并表明TRI3和Tri101 （3-O-trichothecene acetyltransferase， 3-O-trichothecene乙酰转移酶）是进化相关的。TRI3同源物的活性位点残基在所有序列中都是保守的，这表明C15乙酰化的差异不是由于TRI3的差异。tri3缺失突变体表明，尽管DON缺乏C15乙酰基，但DON的生物合成需要C15乙酰化。负责毛霉菌毒素15位去乙酰化的酶尚未确定。
Fusarium head blight is a devastating disease of cereal crops whose worldwide incidence is increasing and at present there is no satisfactory way of combating this pathogen or its associated toxins. There is a wide variety of trichothecene mycotoxins and they all contain a 12,13-epoxytrichothecene skeleton but differ in their substitutions. Indeed, there is considerable variation in the toxin profile across the numerous Fusarium species that has been ascribed to differences in the presence or absence of biosynthetic enzymes and their relative activity. This article addresses the source of differences in acetylation at the C15 position of the trichothecene molecule. Here, we present the in vitro structural and biochemical characterization of TRI3, a 15-O-trichothecene acetyltransferase isolated from F. sporotrichioides and the "in vivo'' characterization of Delta tri3 mutants of deoxynivalenol (DON) producing F. graminearum strains. A kinetic analysis shows that TRI3 is an efficient enzyme with the native substrate, 15-decalonectrin, but is inactive with either DON or nivalenol. The structure of TRI3 complexed with 15-decalonectrin provides an explanation for this specificity and shows that Tri3 and Tri101 (3-O-trichothecene acetyltransferase) are evolutionarily related. The active site residues are conserved across all sequences for TRI3 orthologs, suggesting that differences in acetylation at C15 are not due to differences in Tri3. The tri3 deletion mutant shows that acetylation at C15 is required for DON biosynthesis even though DON lacks a C15 acetyl group. The enzyme(s) responsible for deacetylation at the 15 position of the trichothecene mycotoxins have not been identified.