We previously reported that the BTB (brica-brac, tramtrack, and broad) domain-containing protein Clt1 regulates melanin and toxin synthesis, conidiation, and pathogenicity in Curvularia lunata, but the interacting proteins and regulative mechanism of Clt1 are unclear. In this research, we identified two proteins, which respectively correspond to xylanase (Clxyn24) and acetyl xylan esterase (Claxe43) from C. lunata, that were regulated by Clt1. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation assays were conducted to verify the interaction of Clt1 with full-length Clxyn24 and Claxe43. Furthermore, the Y2H assay revealed that Clt1 physically interacted with Clxyn24 and Claxe43 through its BTB domain to degrade xylan, which was used as a carbon source for C. lunata growth. The utilization of xylan provides acetyl-CoA for the synthesis of melanin and toxin as well as energy and other intermediate metabolites for conidiation. Furthermore, transcriptome analysis revealed that PKS18 and its 13 flanking genes found clustered in a region spanning 57.89 kb on scaffold 9 of the C. lunata CX-3 genome were down-regulated in toxin production–deficient mutant T806, and this cluster is possibly responsible for toxin biosynthesis of C. lunata.

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我们之前曾报道过 BTB（brica-brac、tramtrack 和宽广的）包含域的蛋白质 Clt1 可调节新月弯孢中的黑色素和毒素合成、分生孢子和致病性，但 Clt1 的相互作用蛋白质和调节机制尚不清楚。在本研究中，我们鉴定了两种受 Clt1 调控的蛋白质，分别对应于C. lunata 的木聚糖酶 (Clxyn24) 和乙酰木聚糖酯酶 (Claxe43) 。进行酵母双杂交 (Y2H) 和双分子荧光互补测定以验证 Clt1 与全长 Clxyn24 和 Claxe43 的相互作用。此外，Y2H 分析显示 Clt1 通过其 BTB 结构域与 Clxyn24 和 Claxe43 物理相互作用以降解木聚糖，木聚糖被用作碳源C. lunata生长。木聚糖的利用为黑色素和毒素的合成提供乙酰辅酶 A 以及用于分生孢子的能量和其他中间代谢物。此外，转录组分析显示PKS18及其 13 个侧翼基因聚集在C. lunata CX-3 基因组支架 9 上的 57.89 kb 区域中，在毒素产生缺陷突变体 T806 中下调，该簇可能是负责用于C. lunata 的毒素生物合成。

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