Dürrenberger F, Wong K, Kronstad J W
Biotechnology Laboratory, Departments of Microbiology and Immunology, and Plant Science, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Proc Natl Acad Sci U S A. 1998 May 12;95(10):5684-9. doi: 10.1073/pnas.95.10.5684.
Ustilago maydis, a fungal pathogen of maize, alternates between budding and filamentous growth in response to mating and other environmental signals. Defects in components of the cAMP signaling pathway affect this morphological transition and reveal an association of budding growth with elevated cAMP levels and filamentous growth with low cAMP levels. We have identified two genes, adr1 and uka1, encoding catalytic subunits of cAMP-dependent protein kinase (PKA). Disruption of adr1 resulted in a constitutively filamentous growth phenotype similar to that of mutants deficient in adenylyl cyclase. Importantly, adr1 is required for pathogenicity and is responsible for the majority of PKA activity in fungal cells. In contrast, uka1 has little influence on pathogenicity, and deletion of the uka1 gene does not affect cell morphology. These results provide compelling evidence that regulated PKA activity is crucial during infectious development of U. maydis.
玉米黑粉菌（Ustilago maydis）是玉米的一种真菌病原体，它会根据交配和其他环境信号在出芽生长和丝状生长之间交替。cAMP信号通路成分的缺陷会影响这种形态转变，并揭示出出芽生长与cAMP水平升高相关，而丝状生长与低cAMP水平相关。我们鉴定出了两个基因，adr1和uka1，它们编码cAMP依赖性蛋白激酶（PKA）的催化亚基。adr1的破坏导致了一种组成型丝状生长表型，类似于腺苷酸环化酶缺陷型突变体。重要的是，adr1是致病性所必需的，并且负责真菌细胞中大部分的PKA活性。相比之下，uka1对致病性影响很小，uka1基因的缺失不影响细胞形态。这些结果提供了令人信服的证据，表明受调控的PKA活性在玉米黑粉菌的感染发育过程中至关重要。
