The Hypervariable Amino-Terminus of P1 Protease Modulates Potyviral Replication and Host Defense Responses

PLoS Pathogens

Juan Antonio García¹  Carmen Simón-Mateo¹  Fabio Pasin¹ 

[1] Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain

关键词: Proteases;    Leaves;    Cloning;    Sequence motif analysis;    Viral replication;    Arabidopsis thaliana;    Sequence alignment;    RNA interference;   

DOI  :  10.1371/journal.ppat.1003985

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The replication of many RNA viruses involves the translation of polyproteins, whose processing by endopeptidases is a critical step for the release of functional subunits. P1 is the first protease encoded in plant potyvirus genomes; once activated by an as-yet-unknown host factor, it acts in cis on its own C-terminal end, hydrolyzing the P1-HCPro junction. Earlier research suggests that P1 cooperates with HCPro to inhibit host RNA silencing defenses. Using Plum pox virus as a model, we show that although P1 does not have a major direct role in RNA silencing suppression, it can indeed modulate HCPro function by its self-cleavage activity. To study P1 protease regulation, we used bioinformatic analysis and in vitro activity experiments to map the core C-terminal catalytic domain. We present evidence that the hypervariable region that precedes the protease domain is predicted as intrinsically disordered, and that it behaves as a negative regulator of P1 proteolytic activity in in vitro cleavage assays. In viral infections, removal of the P1 protease antagonistic regulator is associated with greater symptom severity, induction of salicylate-dependent pathogenesis-related proteins, and reduced viral loads. We suggest that fine modulation of a viral protease activity has evolved to keep viral amplification below host-detrimental levels, and thus to maintain higher long-term replicative capacity.

【 授权许可】

CC BY