Multifunctional role of a fungal pathogen-secreted laccase 2 in evasion of insect immune defense
Multifunctional role of a fungal pathogen-secreted laccase 2 in evasion of insect immune defense
复制标题
真菌病原体分泌的漆酶2在逃避昆虫免疫防御中的多功能作用
DOI：
10.1111/1462-2920.15378
复制
发表时间：
2021-01-06
影响因子：
5.1
通讯作者：
Zhang, Yongjun
中科院分区：
文献类型：
--
作者：
Lu, Zhuoyue;Deng, Juan;Zhang, Yongjun
漆酶广泛存在于细菌、真菌、植物和无脊椎动物中，参与多种生理功能。球孢白僵菌是一种经济上重要的昆虫病原真菌，在感染过程中会分泌一种漆酶2(BbLac2)来解毒昆虫免疫应答产生的活性氧(ROS)，并干扰宿主免疫酚氧化酶(PO)的激活。BbLac2在昆虫血腔中的增殖过程中表达于真菌细胞，在体内可发现分布于血淋巴来源的真菌菌丝体表面或分泌。靶向基因敲除BbLac2提高了真菌对氧化胁迫的敏感性，降低了对昆虫的毒力，并增加了寄主PO的活性。过量表达BbLac2的菌株表现出更强的毒力，寄主PO活性降低，感染昆虫体内ROS水平降低。体外实验表明，BbLac2可以清除ROS并氧化PO底物(酚)，验证了该蛋白在解毒细胞毒性ROS和干扰PO级联反应中的酶功能。此外，BbLac2作为一种细胞表面蛋白，掩盖了病原体相关分子模式(PAMPs)，使病原体能够逃避免疫识别。我们的数据表明，真菌病原体分泌的漆酶2在逃避昆虫免疫防御中具有多功能作用。
Laccases are widely present in bacteria, fungi, plants and invertebrates and involved in a variety of physiological functions. Here, we report that Beauveria bassiana, an economic important entomopathogenic fungus, secretes a laccase 2 (BbLac2) during infection that detoxifies insect immune response-generated reactive oxygen species (ROS) and interferes with host immune phenoloxidase (PO) activation. BbLac2 is expressed in fungal cells during proliferation in the insect haemocoel and can be found to distribute on the surface of haemolymph-derived in vivo fungal hyphal bodies or be secreted. Targeted gene-knockout of BbLac2 increased fungal sensitivity to oxidative stress, decreased virulence to insect, and increased host PO activity. Strains overexpressing BbLac2 showed increased virulence, with reduced host PO activity and lowered ROS levels in infected insects. In vitro assays revealed that BbLac2 could eliminate ROS and oxidize PO substrates (phenols), verifying the enzymatic functioning of the protein in detoxification of cytotoxic ROS and interference with the PO cascade. Moreover, BbLac2 acted as a cell surface protein that masked pathogen associated molecular patterns (PAMPs), enabling the pathogen to evade immune recognition. Our data suggest a multifunctional role for fungal pathogen-secreted laccase 2 in evasion of insect immune defenses.