Rao Qi, Guo Wenbin, Chen Xinhua
Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, P.R. China.
J Microbiol Biotechnol. 2015 May;25(5):620-8. doi: 10.4014/jmb.1409.09071.
A fungal strain, R9, was isolated from the South Atlantic sediment sample and identified as Aspergillus fumigatus. An antifungal protein, AfAFPR9, was purified from the culture supernatant of Aspergillus fumigatus R9. AfAFPR9 was identified to be restrictocin, which is a member of the ribosome-inactivating proteins (RIPs), by MALDI-TOF-TOF-MS. AfAFPR9 displayed antifungal activity against plant pathogenic Fusarium oxysporum, Alternaria longipes, Colletotrichum gloeosporioides, Paecilomyces variotii, and Trichoderma viride at minimum inhibitory concentrations of 0.6, 0.6, 1.2, 1.2, and 2.4 μg/disc, respectively. Moreover, AfAFPR9 exhibited a certain extent of thermostability, and metal ion and denaturant tolerance. The iodoacetamide assay showed that the disulfide bridge in AfAFPR9 was indispensable for its antifungal action. The cDNA encoding for AfAFPR9 was cloned from A. fumigatus R9 by RTPCR and heterologously expressed in E. coli. The recombinant AfAFPR9 protein exhibited obvious antifungal activity against C. gloeosporioides, T. viride, and A. longipes. These results reveal the antifungal properties of a RIP member (AfAFPR9) from marine-derived Aspergillus fumigatus and indicated its potential application in controlling plant pathogenic fungi.
从南大西洋沉积物样本中分离出一株真菌菌株R9，并鉴定为烟曲霉。从烟曲霉R9的培养上清液中纯化出一种抗真菌蛋白AfAFPR9。通过基质辅助激光解吸电离飞行时间串联质谱（MALDI-TOF-TOF-MS）鉴定AfAFPR9为限制酶，它是核糖体失活蛋白（RIPs）的成员之一。AfAFPR9对植物病原性尖孢镰刀菌、黑曲霉、胶孢炭疽菌、拟青霉和绿色木霉具有抗真菌活性，其最低抑菌浓度分别为0.6、0.6、1.2、1.2和2.4 μg/圆片。此外，AfAFPR9表现出一定程度的热稳定性以及对金属离子和变性剂的耐受性。碘乙酰胺试验表明，AfAFPR9中的二硫键对其抗真菌作用不可或缺。通过逆转录聚合酶链反应（RT-PCR）从烟曲霉R9中克隆出编码AfAFPR9的cDNA，并在大肠杆菌中进行异源表达。重组AfAFPR9蛋白对胶孢炭疽菌、绿色木霉和黑曲霉表现出明显的抗真菌活性。这些结果揭示了来源于海洋的烟曲霉中一种核糖体失活蛋白成员（AfAFPR9）的抗真菌特性，并表明其在控制植物病原真菌方面的潜在应用价值。
