Division of Applied Life Science (BK21 program), Gyeongsang National University, Jinju 660-701, South Korea.
J Proteome Res. 2011 Jul 1;10(7):3136-48. doi: 10.1021/pr200202m. Epub 2011 Jun 2.
Magnaporthe oryzae is a fungal pathogen that causes blast disease in rice. During its early infection process, during which starvation of nutrients, including nitrogen, prevails before establishment of successful infection, the fungally secreted proteins play an important role in the pathogenicity and stress response. In this study, M. oryzae-secreted proteins were investigated in an N-deficient minimal medium using two-dimensional gel electrophoresis (2-DGE) coupled with mass spectrometry analysis (MALDI-TOF-MS and μLC-ESI-MS/MS). The 2-DGE analysis of secreted proteins detected 89 differentially expressed protein spots (14 downregulated and 75 upregulated) responsive to N starvation. Eighty five of the protein spots were identified by mass spectrometry analyses. Identified proteins were mainly cell wall hydrolase enzymes (22.4%), protein and lipid hydrolases (24.7%), reactive oxygen species detoxifying proteins (22.4%), and proteins with unknown function (14.1%), suggesting early production of prerequisite proteins for successful infection of the host. SignalP analysis predicted the presence of signal peptides in 67% of the identified proteins, suggesting that in addition to the classical Golgi/endoplasmic reticulum secretory pathway, M. oryzae might possess other, as yet undefined, secretory pathways. Those nonclassical or leaderless secretion proteins accounted for 25.9% of the total identified proteins by TatP and SecretomeP predictions. Semiquantitative reverse transcriptase polymerase chain reaction of seven randomly selected N-responsive secreted proteins also revealed a good correlation between RNA and protein levels. Taken together, the establishment of the M. oryzae secretome that is responsive to N starvation provides the first evidence of the secretion of 60 unreported and 25 previously known proteins. This developed protein inventory could be exploited to improve our understanding of the secretory mechanisms of M. oryzae and its invasive growth process in rice tissue.
稻瘟病菌是一种真菌病原体,可导致水稻稻瘟病。在其早期感染过程中,在成功感染之前,包括氮在内的营养物质会出现饥饿,真菌分泌的蛋白质在致病性和应激反应中发挥重要作用。在这项研究中,使用二维凝胶电泳(2-DGE)结合质谱分析(MALDI-TOF-MS 和 μLC-ESI-MS/MS)在缺氮的最小培养基中研究了稻瘟病菌分泌的蛋白质。分泌蛋白的 2-DGE 分析检测到 89 个对氮饥饿有反应的差异表达蛋白斑点(14 个下调和 75 个上调)。通过质谱分析鉴定了 85 个蛋白斑点。鉴定的蛋白质主要是细胞壁水解酶(22.4%)、蛋白质和脂质水解酶(24.7%)、活性氧解毒蛋白(22.4%)和功能未知的蛋白(14.1%),这表明早期产生了成功感染宿主所需的前提蛋白。SignalP 分析预测,在鉴定出的蛋白质中,有 67%存在信号肽,这表明除了经典的高尔基体/内质网分泌途径外,稻瘟病菌可能还具有其他尚未定义的分泌途径。TatP 和 SecretomeP 的预测表明,这些非经典或无信号肽的分泌蛋白占总鉴定蛋白的 25.9%。对 7 个随机选择的 N 反应性分泌蛋白的半定量逆转录聚合酶链反应也揭示了 RNA 和蛋白质水平之间的良好相关性。总之,建立了对氮饥饿有反应的稻瘟病菌分泌组,为分泌 60 种未报道和 25 种先前已知蛋白质提供了第一个证据。该开发的蛋白质清单可用于更好地了解稻瘟病菌的分泌机制及其在水稻组织中的侵袭性生长过程。