A putative branched-chain-amino-acid transaminase gene required for HC-toxin biosynthesis and pathogenicity in Cochliobolus carbonum
A putative branched-chain-amino-acid transaminase gene required for HC-toxin biosynthesis and pathogenicity in Cochliobolus carbonum
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DOI：
10.1099/00221287-145-12-3539
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发表时间：
1999-12-01
期刊：
影响因子：
--
通讯作者：
Walton, JD
中科院分区：
文献类型：
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作者：
Cheng, YQ;Ahn, JH;Walton, JD
环状四肽HC-毒素是丝状真菌Cochliobolus carbonum对玉米致病所必需的。HC-毒素的产生由复杂的基因座TOX 2控制。TOX 2基因座的一个新基因TOXF的分离和鉴定。本文报道它表明，TOXF是专门需要HC-毒素的生产和致病性。它在所有HC-毒素产生（Tox 2（+））分离株中以两个或三个拷贝存在，在毒素非产生菌株中不存在。推测的氨基酸序列与许多已知或推测的来自不同物种的支链氨基酸转氨酶具有中等的同源性。梭菌的菌株所有TOXF拷贝都被破坏的碳藻生长正常，但丧失了HC毒素产生和致病性。有人提出，TOXF在HC-毒素合成中具有生物合成作用，可能胺化Aeo（2-氨基-9，10-环氧-8-氧代癸酸）的前体。
The cyclic tetrapeptide HC-toxin is required for pathogenicity of the filamentous fungus Cochliobolus carbonum on maize. HC-toxin production is controlled by a complex locus, TOX2. The isolation and characterization of a new gene of the TOX2 locus, TOXF. is reported. It is shown that TOXF is specifically required for HC-toxin production and pathogenicity. It is present as two or three copies in all HC-toxin-producing (Tox2(+)) isolates and is absent in toxin-non-producing strains. The deduced amino acid sequence of TOXF has moderate homology to many known or putative branched-chain-amino-acid transaminases from various species. A strain of C. carbonum with all copies of TOXF disrupted grew normally but lost HC-toxin production and pathogenicity. It is proposed that TOXF has a biosynthetic role in HC-toxin synthesis, perhaps to aminate a precursor of Aeo (2-amino-9,10-epoxi-8-oxodecanoic acid).