Proctor R H, Desjardins A E, Plattner R D, Hohn T M
Mycotoxin Research Unit, National Center for Agricultural Utilization Research, Peoria, Illinois 61604, USA.
Fungal Genet Biol. 1999 Jun;27(1):100-12. doi: 10.1006/fgbi.1999.1141.
Fumonisins are toxins associated with several mycotoxicoses and are produced by the maize pathogen Gibberella fujikuroi mating population A (MP-A). Biochemical analyses indicate that fumonisins are a product of either polyketide or fatty acid biosynthesis. To isolate a putative polyketide synthase (PKS) gene involved in fumonisin biosynthesis, we employed PCR with degenerate PKS primers and a cDNA template prepared from a fumonisin-producing culture of G. fujikuroi. Sequence analysis of the single PCR product and its flanking DNA revealed a gene (FUM5) with a 7.8-kb coding region. The predicted FUM5 translation product was highly similar to bacterial and fungal Type I PKSs. Transformation of a cosmid clone carrying FUM5 into G. fujikuroi enhanced production in three strains and restored wild-type production in a fumonisin nonproducing mutant. Disruption of FUM5 reduced fumonisin production by over 99% in G. fujikuroi MP-A. Together, these results indicate that FUM5 is a PKS gene required for fumonisin biosynthesis.
伏马菌素是与多种霉菌毒素中毒相关的毒素，由玉米病原菌藤仓赤霉交配型A（MP-A）产生。生化分析表明，伏马菌素是聚酮化合物或脂肪酸生物合成的产物。为了分离参与伏马菌素生物合成的假定聚酮合酶（PKS）基因，我们使用简并PKS引物和从产生伏马菌素的藤仓赤霉培养物制备的cDNA模板进行PCR。对单个PCR产物及其侧翼DNA的序列分析揭示了一个具有7.8 kb编码区的基因（FUM5）。预测的FUM5翻译产物与细菌和真菌的I型聚酮合酶高度相似。将携带FUM5的黏粒克隆转化到藤仓赤霉中，在三个菌株中提高了产量，并在一个不产生伏马菌素的突变体中恢复了野生型产量。FUM5的破坏使藤仓赤霉MP-A中的伏马菌素产量降低了99%以上。这些结果共同表明，FUM5是伏马菌素生物合成所需的PKS基因。
