title: Gemin5 proteolysis reveals a novel motif to identify L protease targets.
abstract: Translation of picornavirus RNA is governed by the internal ribosome entry site (IRES) element, directing the synthesis of a single polyprotein. Processing of the polyprotein is performed by viral proteases that also recognize as substrates host factors. Among these substrates are translation initiation factors and RNA-binding proteins whose cleavage is responsible for inactivation of cellular gene expression. Foot-and-mouth disease virus (FMDV) encodes two proteases, L(pro) and 3C(pro). Widespread definition of L(pro) targets suffers from the lack of a sufficient number of characterized substrates. Here, we report the proteolysis of the IRES-binding protein Gemin5 in FMDV-infected cells, but not in cells infected by other picornaviruses. Proteolysis was specifically associated with expression of L(pro), yielding two stable products, p85 and p57. In silico search of putative L targets within Gemin5 identified two sequences whose potential recognition was in agreement with proteolysis products observed in infected cells. Mutational analysis revealed a novel L(pro) target sequence that included the RKAR motif. Confirming this result, the Fas-ligand Daxx, was proteolysed in FMDV-infected and L(pro)-expressing cells. This protein carries a RRLR motif whose substitution to EELR abrogated L(pro) recognition. Thus, the sequence (R)(R/K)(L/A)(R) defines a novel motif to identify putative targets of L(pro) in host factors.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Piñeiro
authors.forename: Jorge
authors.initials: J
authors.lastname: Ramajo
authors.forename: Shelton S
authors.initials: SS
authors.lastname: Bradrick
authors.forename: Encarnación
authors.initials: E
authors.lastname: Martínez-Salas
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D010450:Endopeptidases / Q000378:metabolism*; D029544:Foot-and-Mouth Disease Virus / Q000502:physiology; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D059748:Proteolysis; D055532:SMN Complex Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D055532:SMN Complex Proteins; D010450:Endopeptidases; C088747:leader proteinase, foot-and-mouth disease virus