A fatty acid synthase gene in Cochliobolus carbonum required for production of HC-toxin, cyclo(D-prolyl-L-alanyl-D-alanyl-L-2-Amino-9,10-epoxi-8-oxodecanoyl)
A fatty acid synthase gene in Cochliobolus carbonum required for production of HC-toxin, cyclo(D-prolyl-L-alanyl-D-alanyl-L-2-Amino-9,10-epoxi-8-oxodecanoyl)
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DOI：
10.1094/mpmi.1997.10.2.207
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发表时间：
1997-03-01
影响因子：
3.5
通讯作者：
Walton, JD
中科院分区：
文献类型：
--
作者：
Ahn, JH;Walton, JD
玉米病原真菌炭旋孢菌产生一种具有植物毒性和细胞生长抑制作用的环肽，HC-毒素，其结构为环（D-脯氨酰-L-丙氨酰-D-丙氨酰-L-Aeo），其中Aeo代表2-氨基-9，10-环氧-8-氧代癸酸。在此，我们报道了仅存在于HC-毒素产生（Tox 2（+））真菌菌株中的基因TOXC的分离，TOXC以三个功能性拷贝存在于大多数Tox 2（+）菌株中，所有这些拷贝都与编码HC-毒素合成酶的基因在同一染色体上。当TOXC的所有拷贝通过靶向基因破坏而突变时，真菌在体外正常生长和孢子形成，但不再产生HC-毒素并且不是致病性的，表明TOXC在HC-毒素产生中具有特异性作用，因此毒性也是如此。TOXC mRNA为6.5 kb，预测产物具有2，080个氨基酸，分子量为233，000。一级氨基酸序列与来自几种低等真核生物的脂肪酸合成酶的β亚基高度相似（45至47%同一性），并且以与其他β亚基相同的顺序含有预测编码乙酰转移酶、烯酰还原酶、脂肪酶和丙二酰-棕榈酰转移酶的结构域。TOXC最合理的功能是有助于合成Aeo的癸酸骨架。
The fungal maize pathogen Cochliobolus carbonum produces a phytotoxic and cytostatic cyclic peptide, HC-toxin, of structure cyclo(D-prolyl-L-alanyl-D-alanyl-L-Aeo), in which Aeo stands for 2-amino-9,10-epoxi-8-oxodecanoic acid, Here we report the isolation of a gene, TOXC, that is present only in HC-toxin-producing (Tox2(+)) fungal strains, TOXC is present in most Tox2(+) strains in three functional copies, all of which are on the same chromosome as the gene encoding HC-toxin synthetase, When all copies of TOXC are mutated by targeted gene disruption, the fungus grows and sporulates normally in vitro but no longer makes HC-toxin and is not pathogenic, indicating that TOXC has a specific role in HC-toxin production and hence virulence. The TOXC mRNA is 6.5 kb and the predicted product has 2,080 amino acids and a molecular weight of 233,000. The primary amino acid sequence is highly similar (45 to 47% identity) to the beta subunit of fatty acid synthase from several lower eukaryotes, and contains, in the same order as in other beta subunits, domains predicted to encode acetyl transferase, enoyl reductase, dehydratase, and malonyl-palmityl transferase, The most plausible function of TOXC is to contribute to the synthesis of the decanoic acid backbone of Aeo.