The C-terminal MIR-containing region in the Pmt1 O-mannosyltransferase restrains sporulation and is dispensable for virulence in Beauveria bassiana
The C-terminal MIR-containing region in the Pmt1 O-mannosyltransferase restrains sporulation and is dispensable for virulence in Beauveria bassiana
复制标题
Pmt1 O-甘露糖基转移酶中的 C 端含有 MIR 的区域抑制孢子形成，并且对于白僵菌的毒力来说是可有可无的
DOI：
10.1007/s00253-016-7894-9
复制
发表时间：
2017-02-01
影响因子：
5
通讯作者：
Zhang, Yongjun
中科院分区：
文献类型：
--
作者：
He, Zhangjiang;Luo, Linli;Zhang, Yongjun
蛋白质O - 甘露糖基转移酶（Pmts）属于一个高度保守的蛋白质家族，负责许多蛋白质O - 糖基化的起始过程。Pmts包含一个磷酸多萜醇 - 甘露糖 - 蛋白质甘露糖基转移酶（PMT）结构域和三个MIR基序（甘露糖基转移酶、三磷酸肌醇和兰尼碱受体），这些对于酵母中的相关活性至关重要。我们报告称，在昆虫病原真菌球孢白僵菌中，缺失Pmt1 C端含MIR的区域（Pmt1Δ(311 - 902)）不会改变O - 甘露糖基转移酶的活性，但会增加细胞壁总蛋白的O - 甘露糖基化水平，并导致真菌发育和细胞壁稳定性方面的表型变化。与野生型亲本相比，携带Pmt1Δ(311 - 902)突变的球孢白僵菌突变体在产孢方面显著增加，产孢相关基因上调，生物量积累也有所增加。然而，营养生长和芽生孢子产生减少，并且Pmt1Δ(311 - 902)突变体的细胞壁组成和细胞表面特征发生了改变。昆虫生物测定显示，通过体壁感染或血腔注射测定，Pmt1Δ(311 - 902)菌株的毒力影响不大，尽管在宿主体内血淋巴中菌丝体分化存在差异且毒力相关基因上调。这些数据表明Pmt1在负调控产孢方面具有新的作用，并证明Pmt1 C端含MIR的区域对于酶活性和生物体毒力并非必需。
Protein O-mannosyltransferases (Pmts) belong to a highly conserved protein family responsible for the initiation of O-glycosylation of many proteins. Pmts contain one dolichyl-phosphate-mannose-protein mannosyltransferases (PMT) domain and three MIR motifs (mannosyltransferase, inositol triphosphate, and ryanodine receptor) that are essential for activity in yeast. We report that in the insect fungal pathogen, Beauveria bassiana, deletion of the C-terminal Pmt1 MIR-containing region (Pmt1∆311-902) does not alter O-mannosyltransferase activity, but does increase total cell wall protein O-mannosylation levels and results in phenotypic changes in fungal development and cell wall stability. B. bassiana mutants harboring the Pmt1 ∆311-902mutation displayed a significant increase in conidiation with up-regulation of conidiation-associated genes and an increase in biomass accumulation as compared to the wild-type parent. However, decreased vegetative growth and blastospore production was noted, and Pmt1 ∆311-902mutants were altered in cell wall composition and cell surface features. Insect bioassays revealed little effect on virulence for the Pmt1 ∆311-902strain via cuticle infection or intrahemocoel injection assays, although differences in hyphal body differentiation in the host hemolymph and up-regulation of virulence-associated genes were noted. These data suggest novel roles for Pmt1 in negatively regulating conidiation and demonstrate that the C-terminal Pmt1 MIR-containing region is dispensable for enzymatic activity and organismal virulence.