State Key Program of Microbiology and Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
Microbiol Res. 2017 Oct;203:29-39. doi: 10.1016/j.micres.2017.06.003. Epub 2017 Jun 15.
G-protein-mediated signaling pathways regulate fungal morphogenesis, development and secondary metabolism. In this study, we report a gene, pgα1, that putatively encodes the α-subunit of a group I G protein in Pestalotiopsis microspora NK17, which is known to produce various secondary metabolites, including the antitumor drug taxol and pestalotiollide B (PB). Mutants of pgα1 showed retarded vegetative growth, aging of the mycelium, premature conidiation, deformed conidia, significantly increased melanin production, and a sharp decrease in PB production. The introduction of extra copies of pgα1 led to a different phenotype that was characterized by enhanced production of PB. qRT-PCR revealed that the expression of pks1, which encodes melanin polyketide synthase, an enzyme that is involved in 1, 8-dihydroxynaphthalene (DHN) melanin biosynthesis, was up regulated by 55-fold in the absence of pgα1. Changes in conidiation and PB production in pgα1 mutants were able to be restored by the addition of exogenous cAMP. The deficiencies of PB production and conidiation in Δpgα1 were not able to be rescued by deletion or overexpression of a previously reported histone deacetylase gene (hid1), suggesting that pgα1 is able to override the effect of hid1 on PB production and conidiation. Our results suggested that the G protein-cAMP pathway plays a critical role in vegetative growth as well as in asexual development of P. microspora.
G 蛋白介导的信号通路调节真菌形态发生、发育和次生代谢。在这项研究中，我们报告了一个基因，pgα1，它可能编码 Pestalotiopsis microspora NK17 中 I 组 G 蛋白的 α 亚基，该基因已知能产生各种次生代谢物，包括抗肿瘤药物紫杉醇和 pestalotiollide B（PB）。pgα1 突变体表现出生长缓慢、菌丝老化、过早产孢、畸形分生孢子、黑色素产量显著增加和 PB 产量急剧下降。额外拷贝 pgα1 的引入导致了不同的表型，其特征是 PB 产量增加。qRT-PCR 显示，编码黑色素聚酮合酶的 pks1 的表达在没有 pgα1 的情况下上调了 55 倍，该酶参与 1,8-二羟基萘（DHN）黑色素生物合成。pgα1 突变体中分生孢子形成和 PB 产量的变化可以通过添加外源性 cAMP 来恢复。Δpgα1 中 PB 产量和分生孢子形成的缺陷不能通过缺失或过表达先前报道的组蛋白去乙酰化酶基因（hid1）来挽救，这表明 pgα1 能够克服 hid1 对 PB 产量和分生孢子形成的影响。我们的结果表明，G 蛋白-cAMP 途径在 Pestalotiopsis microspora 的营养生长以及无性发育中起着关键作用。
