稻瘟病菌CAAX蛋白酶MoRce1的功能研究

Functional characterization of a CAAX protease MoRce1 in Magnaporthe oryzae

蛋白质的翻译后异戊烯化修饰(CAAX修饰)能够介导真核生物中许多重要蛋白质的亚细胞定位以及蛋白与蛋白间的相互作用。稻瘟病菌(Magnaporthe oryzae)引致的稻瘟病是水稻最重要病害之一,造成全球水稻严重减产。为深入了解稻瘟病菌致病机理,更好地防控稻瘟病,我们研究了异戊烯修饰是否影响稻瘟病菌的生长发育和致病性。首先从稻瘟病菌基因组数据库中鉴定到一个稻瘟病菌的异戊烯蛋白酶MoRce1,同源比对发现MoRce1保守结构域在各物种之间变化较大,猜测在不同物种中该蛋白可能出现了功能分化。经同源重组方法敲除MoRCE1基因,发现MoRCE1缺失突变体在胁迫培养条件下细胞壁完整性明显缺陷,但是对营养生长、产孢、萌发以及致病性没有明显影响,说明MoRce1蛋白可能通过参与稻瘟病菌细胞壁合成相关蛋白的异戊烯化修饰进而影响该菌细胞壁的完整性,其具体机制还有待深入研究。

Post-translational prenylation pathway(CAAX modification) mediates many subcellular localization of critical proteins and protein-protein interactions in eukaryotes. The rice blast fungus Magnaporthe oryzae causes one of most important diseases and results in dramatic yield loss of rice around the world. To further understand the pathogenesis and to better control the rice blast disease, we examined whether the post-translational prenylation pathway plays a role in the fungal development and pathogenicity. We identified a CAAX prenyl protease MoRce1 from M. oryzae genome database. Domain prediction revealed that the conserved domain of MoRce1 is significantly distinct to Rce1 homologs from different species, suggesting that Rce1 may evolve into different functions. Deletion of MoRCE1 through homologous recombination exhibited growth defects under cell wall stress conditions, while the vegetative growth, conidiation, germination, and pathogenicity show no significant defects in the gene deletion mutant. In summary, our results suggested that MoRce1 may participate in the modification of cell wall synthesis-related proteins but it does not play a role in the pathogenicity of M. oryzae.