{PDOC51744} {PS51744; HC_PRO_CPD} {BEGIN} ******************************************************************************* * Helper-component proteinase (HC-Pro) cysteine protease (CPD) domain profile * ******************************************************************************* Potyviruses form one of the most numerous groups of plant viruses and are a major cause of crop loss worldwide. The helper-component proteinase (HC-Pro) is an indispensable, multifunctional protein of members of the genus Potyvirus and other viruses of the family Potyviridae [E1]. It is directly involved in diverse steps of viral infection, such as aphid plant-to-plant transmission, polyprotein processing, and suppression of host antiviral RNA silencing. HC- Pro is generally divided into three functional domains: a N-terminal domain, a central region, and a cysteine protease domain (CPD) in the C-terminal region. The HC-Pro CPD domain has a protease activity that autocatalytically cleaves a Gly-Gly dipeptide at its own C terminus to release HC-Pro from the rest of the viral polyprotein. Cysteine and histidine residues form the catalytic dyad at the active site. The HC-Pro CPD domain constitutes the peptidase family C6 of the CA clan [1,E2]. The structure of the HC-Pro CPD domain adopts a compact oval-shaped alpha/beta fold. The secondary structure elements include four alpha-helices (alpha1- alpha4) and two short beta-strands (beta1 and beta2) arranged in the order alpha1-alpha2-alpha3-beta1-beta2-alpha4. In addition, two 3(10) helices are located between alpha3 and beta1 and downstream of alpha4. The four helices form a helix bundle packed against one face of a short beta-hairpin formed by strands beta1 and beta2 (see ). The catalytic residue Cys is located at the N terminus of helix alpha1, and the other catalytic residue His is located on strand beta2. The substrate binding cleft is lined by the loop connecting helices alpha2 and alpha3 and the N-terminal region of helix alpha1 on one side and by strand beta2 on the other side [1]. The profile we developed covers the entire HC-Pro CPD domain. -Sequences known to belong to this class detected by the profile: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Last update: January 2015 / First entry. [ 1] Guo B., Lin J., Ye K. "Structure of the autocatalytic cysteine protease domain of potyvirus helper-component proteinase." J. Biol. Chem. 286:21937-21943(2011). PubMed=21543324; DOI=10.1074/jbc.M111.230706 [E1] https://viralzone.expasy.org/48?outline=all_by_species [E2] https://www.ebi.ac.uk/merops/cgi-bin/merops.cgi?id=C6 -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}