PAPAIN-LIKE PROTEASE-P-29 AS A SYMPTOM DETERMINANT ENCODED BY A HYPOVIRULENCE-ASSOCIATED VIRUS OF THE CHESTNUT BLIGHT FUNGUS
PAPAIN-LIKE PROTEASE-P-29 AS A SYMPTOM DETERMINANT ENCODED BY A HYPOVIRULENCE-ASSOCIATED VIRUS OF THE CHESTNUT BLIGHT FUNGUS
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DOI：
10.1128/jvi.67.11.6513-6521.1993
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发表时间：
1993-11-01
影响因子：
5.4
通讯作者：
NUSS, DL
中科院分区：
文献类型：
--
作者：
CRAVEN, MG;PAWLYK, DM;NUSS, DL
病毒双链 RNA (dsRNA) 负责板栗疫病真菌 Cryphonectria parasitica 的毒力减弱（低毒力），除了毒力外，还深刻影响一系列宿主功能。低毒力菌株 EP713 中存在的原型低毒力相关病毒 dsRNA L-dsRNA 的 5'-近端开放阅读框 A 最近通过 DNA 介导的转化分析显示可抑制真菌孢子形成、色素沉着和漆酶的积累（G. H. Choi 和 D. L. Nuss，EMBO J. 11：473-477， 1992）。我们将这种抑制活性映射到自催化类木瓜蛋白酶 p29，该蛋白酶存在于开放阅读框 A 编码的多蛋白 p69 的氨基末端部分。突变分析表明，p29 改变真菌表型的能力取决于多蛋白前体的释放，但与内在的蛋白水解活性无关。在感染性 L-dsRNA cDNA 克隆的背景下删除 p29 编码结构域会产生具有复制能力的病毒 dsRNA，该病毒 dsRNA 表现出中等抑制活性，同时保留赋予低毒力的能力。因此，p29 对于野生型低毒力菌株 EP713 观察到的病毒介导的真菌色素沉着、孢子形成和漆酶积累的抑制水平是必需的，但还不够，并且对于病毒 RNA 复制和毒力减弱来说不是必需的。这些结果还说明了设计感染性病毒 cDNA 以构建具有特定表型特征的低毒力真菌菌株的可行性。
Viral double-stranded RNAs (dsRNAs) responsible for virulence attenuation (hypovirulence) of the chestnut blight fungus, Cryphonectria parasitica, profoundly influence a range of host functions in addition to virulence. The 5'-proximal open reading frame, A, of the prototypical hypovirulence-associated viral dsRNA, L-dsRNA, present in hypovirulent strain EP713, was recently shown by DNA-mediated transformation analysis to suppress fungal sporulation, pigmentation, and accumulation of the enzyme laccase (G. H. Choi and D. L. Nuss, EMBO J. 11:473-477, 1992). We mapped this suppressive activity to the autocatalytic papain-like protease, p29, present within the amino-terminal portion of open reading frame A-encoded polyprotein p69. Mutational analysis revealed that the ability of p29 to after fungal phenotype is dependent upon release from the polyprotein precursor but is independent of intrinsic proteolytic activity. Deletion of the p29-coding domain within the context of an infectious L-dsRNA cDNA clone resulted in a replication-competent viral dsRNA that exhibited intermediate suppressive activity while retaining the ability to confer hypovirulence. Thus, p29 is necessary but not sufficient for the level of virus-mediated suppression of fungal pigmentation, sporulation, and laccase accumulation observed for wild-type hypovirulent strain EP713 and is nonessential for viral RNA replication and virulence attenuation. These results also illustrate the feasibility of engineering infectious viral cDNA for construction of hypovirulent fungal strains with specific phenotypic traits.