ras2 controls morphogenesis, pheromone response, and pathogenicity in the fungal pathogen Ustilago maydis
ras2 controls morphogenesis, pheromone response, and pathogenicity in the fungal pathogen Ustilago maydis
复制标题
DOI：
10.1128/ec.1.6.954-966.2002
复制
发表时间：
2002-12-01
期刊：
影响因子：
--
通讯作者：
Kronstad, JW
中科院分区：
文献类型：
--
作者：
Lee, N;Kronstad, JW
玉米黑粉菌是玉米的一种病原菌，是分析真菌交配、致病性以及芽殖和丝状生长之间形态转变的有用模型。与其他真菌一样，这些过程受到保守信号传导机制的调节，包括环AMP（cAMP）/蛋白激酶A（PKA）途径和至少一种促分裂原活化蛋白激酶（MAP激酶）途径。目前的一个挑战是确定其他因素，位于下游的cAMP途径和影响形态发生在美国。玉米粉在这项研究中，我们确定了抑制突变，恢复芽生长的组成型丝状突变体的PKA的催化亚基编码基因的缺陷。一个抑制突变的互补意外地确定了ras 2基因，该基因被预测为编码保守的ras家族的小GTP结合蛋白的成员。在单倍体细胞中缺失ras 2基因改变了细胞形态，消除了对玉米幼苗的致病性，并揭示了在交配过程中气生菌丝的产生中的作用。我们还使用了一个激活的Ras 2等位基因，以证明Ras 2促进假菌丝生长通过MAP激酶级联涉及MAP激酶Fuz 7和MAP激酶Ubc 3。总的来说，我们的研究结果揭示了一个额外的水平之间的串扰cAMP信号通路和MAP激酶途径的影响Ras 2。
Ustilago maydis, a pathogen of maize, is a useful model for the analysis of mating, pathogenicity, and the morphological transition between budding and filamentous growth in fungi. As in other fungi, these processes are regulated by conserved signaling mechanisms, including the cyclic AMP (cAMP)/protein kinase A (PKA) pathway and at least one mitogen-activated protein kinase (MAP kinase) pathway. A current challenge is to identify additional factors that lie downstream of the cAMP pathway and that influence morphogenesis in U. maydis. In this study, we identified suppressor mutations that restored budding growth to a constitutively filamentous mutant with a defect in the gene encoding a catalytic subunit of PKA. Complementation of one suppressor mutation unexpectedly identified the ras2 gene, which is predicted to encode a member of the well-conserved ras family of small GTP-binding proteins. Deletion of the ras2 gene in haploid cells altered cell morphology, eliminated pathogenicity on maize seedlings, and revealed a role in the production of aerial hyphae during mating. We also used an activated ras2 allele to demonstrate that Ras2 promotes pseudohyphal growth via a MAP kinase cascade involving the MAP kinase kinase Fuz7 and the MAP kinase Ubc3. Overall, our results reveal an additional level of crosstalk between the cAMP signaling pathway and a MAP kinase pathway influenced by Ras2.