THE TRI4 GENE OF FUSARIUM SPOROTRICHIOIDES ENCODES A CYTOCHROME-P450 MONOOXYGENASE INVOLVED IN TRICHOTHECENE BIOSYNTHESIS
THE TRI4 GENE OF FUSARIUM SPOROTRICHIOIDES ENCODES A CYTOCHROME-P450 MONOOXYGENASE INVOLVED IN TRICHOTHECENE BIOSYNTHESIS
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DOI：
10.1007/bf02456618
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发表时间：
1995-07-22
期刊：
影响因子：
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通讯作者：
MCCORMICK, SP
中科院分区：
文献类型：
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作者：
HOHN, TM;DESJARDINS, AE;MCCORMICK, SP
通过Tri 4（-）突变体的互补，从带有Tri 5基因的克隆DNA片段中分离了孢毛状镰刀菌Tri 4基因。测定了Tri 4基因的核苷酸序列，并确定了三个内含子的位置。Tri 4 mRNA水平的分析表明，转录达到最高水平与开始的二萜二烯生物合成，然后下降20倍，在接下来的8小时。Tri 4的破坏导致了两种倍半萜和阿朴二醇的生产损失以及未氧化途径中间体阿朴二烯的积累。缺乏功能性Tri 4基因的转化体能够将早期途径中间体异毛三醇转化为T-2毒素，这表明大多数途径酶存在于Tri 4（-）突变体中。这些数据表明，由Tri 4编码的酶催化的第一个氧化步骤中的倍半萜途径，并参与apopodiol生物合成。Tri 4编码一个520个残基的蛋白质（M（r）= 59 056），该蛋白质与细胞色素P450超家族的成员具有显著的同源性。它似乎与CYP 3A亚家族最相似（24.6%氨基酸同一性）。由于Tri 4基因与其他细胞色素P450的位置同一性低于40%，因此Tri 4基因被归入一个新的细胞色素P450基因家族，命名为CYP 58。
The Tri4 gene of Fusarium sporotrichioides was isolated from a cloned DNA fragment carrying the Tri5 gene by complementation of a Tri4(-) mutant. The nucleotide sequence of Tri4 was determined and the locations of three introns were identified. Analysis of Tri4 mRNA levels revealed that transcription reached maximum levels coincidently with the onset of trichothecene biosynthesis, and then declined 20-fold over the next 8 h. Disruption of Tri4 resulted in the loss of production of both trichothecenes and apotrichodiol and the accumulation of the unoxygenated pathway intermediate trichodiene. Transformants lacking a functional Tri4 gene were able to convert isotrichotriol, an early pathway intermediate, to T-2 toxin suggesting that most pathway enzymes are present in Tr4(-) mutants. These data suggest that the enzyme encoded by Tri4 catalyzes the first oxygenation step in the trichothecene pathway and participates in apotrichodiol biosynthesis. Tri4 encodes a protein of 520 residues (M(r) = 59 056) that shows significant homology with members of the superfamily of cytochromes P450. It appears most similar to the CYP3A subfamily (24.6% amino acid identity). Because it contains less than 40% positional identity with other cytochromes P450, the Tri4 gene has been placed in a new cytochrome P450 gene family designated CYP58.