Park Hee-Soo, Man Yu Yeong, Lee Mi-Kyung, Jae Maeng Pil, Chang Kim Sun, Yu Jae-Hyuk
Department of Bacteriology, University of Wisconsin, Madison, WI, USA.
Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Republic of Korea.
Sci Rep. 2015 May 11;5:10199. doi: 10.1038/srep10199.
Beta-glucans are a heterologous group of fibrous glucose polymers that are a major constituent of cell walls in Ascomycetes and Basidiomycetes fungi. Synthesis of β (1,3)- and (1,6)-glucans is coordinated with fungal cell growth and development, thus, is under tight genetic regulation. Here, we report that β-glucan synthesis in both asexual and sexual spores is turned off by the NF-kB like fungal regulators VosA and VelB in Aspergillus nidulans. Our genetic and genomic analyses have revealed that both VosA and VelB are necessary for proper down-regulation of cell wall biosynthetic genes including those associated with β-glucan synthesis in both types of spores. The deletion of vosA or velB results in elevated accumulation of β-glucan in asexual spores. Double mutant analyses indicate that VosA and VelB play an inter-dependent role in repressing β-glucan synthesis in asexual spores. In vivo chromatin immuno-precipitation analysis shows that both VelB and VosA bind to the promoter region of the β-glucan synthase gene fksA in asexual spores. Similarly, VosA is required for proper repression of β-glucan synthesis in sexual spores. In summary, the VosA-VelB hetero-complex is a key regulatory unit tightly controlling proper levels of β-glucan synthesis in asexual and sexual spores.
β-葡聚糖是一类异源的纤维状葡萄糖聚合物，是子囊菌和担子菌细胞壁的主要成分。β（1,3）-和（1,6）-葡聚糖的合成与真菌细胞的生长和发育相协调，因此受到严格的基因调控。在此，我们报道在构巢曲霉中，类似NF-kB的真菌调节因子VosA和VelB可关闭无性和有性孢子中的β-葡聚糖合成。我们的遗传和基因组分析表明，VosA和VelB对于正确下调细胞壁生物合成基因（包括与两种类型孢子中β-葡聚糖合成相关的基因）都是必需的。vosA或velB的缺失导致无性孢子中β-葡聚糖的积累增加。双突变分析表明，VosA和VelB在抑制无性孢子中的β-葡聚糖合成中发挥相互依赖的作用。体内染色质免疫沉淀分析表明，VelB和VosA都与无性孢子中β-葡聚糖合酶基因fksA的启动子区域结合。同样，VosA对于有性孢子中β-葡聚糖合成的适当抑制也是必需的。总之，VosA-VelB异源复合物是一个关键的调控单元，紧密控制无性和有性孢子中β-葡聚糖合成的适当水平。
