Liu Xinyu, Cai Yongchao, Zhang Xi, Zhang Haifeng, Zheng Xiaobo, Zhang Zhengguang
Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University Nanjing, China.
Front Microbiol. 2016 Dec 19;7:2023. doi: 10.3389/fmicb.2016.02023. eCollection 2016.
Arginine is a semi-essential amino acid that affects physiological and biochemical functions. The gene in yeast encodes a large subunit of arginine-specific carbamoyl phosphate synthetase (CPS) and is involved in arginine biosynthesis. Here, an ortholog of yeast was identified in the rice blast fungus , and was named . MoCpa2 is an 1180-amino acid protein which contains an ATP grasp domain and two CPSase domains. Targeted deletion of supported its role in arginine biosynthesis in as mutant phenotypes were complemented by arginine but not ornithine. The Δ mutant exhibited defects in asexual development and pathogenicity but not appressorium formation. Further examination revealed that the invasive hyphae of the Δ mutant were restricted mainly to the primary infected cells. In addition, the Δ mutant was unable to induce a plant defense response and had the ability to scavenge ROS during pathogen-plant interactions. Structure analysis revealed that the ATP grasp domain and each CPS domain were indispensable for the proper localization and full function of MoCpa2. In summary, our results indicate that MoCpa2 plays an important role in arginine biosynthesis, and affects growth, conidiogenesis, and pathogenicity. These results suggest that research into metabolism and processes that mediate amino acid synthesis are valuable for understanding pathogenesis.
精氨酸是一种影响生理和生化功能的半必需氨基酸。酵母中的该基因编码精氨酸特异性氨甲酰磷酸合成酶（CPS）的大亚基，并参与精氨酸的生物合成。在此，在稻瘟病菌中鉴定出酵母的一个直系同源基因，并将其命名为MoCpa2。MoCpa2是一种含有1180个氨基酸的蛋白质，包含一个ATP结合结构域和两个CPSase结构域。对MoCpa2进行靶向缺失证实了其在稻瘟病菌精氨酸生物合成中的作用，因为突变表型可被精氨酸而非鸟氨酸互补。ΔMoCpa2突变体在无性发育和致病性方面表现出缺陷，但附着胞形成正常。进一步研究发现，ΔMoCpa2突变体的侵染菌丝主要局限于最初感染的细胞。此外，ΔMoCpa2突变体无法诱导植物防御反应，并且在病原菌与植物相互作用过程中具有清除活性氧的能力。结构分析表明，ATP结合结构域和每个CPS结构域对于MoCpa2的正确定位和完整功能是不可或缺的。总之，我们的结果表明MoCpa2在精氨酸生物合成中起重要作用，并影响生长、分生孢子形成和致病性。这些结果表明，研究介导氨基酸合成的代谢和过程对于理解稻瘟病菌的致病机制具有重要价值。
