title: IRES-driven translation is stimulated separately by the FMDV 3'-NCR and poly(A) sequences.
abstract: The 3' end region of foot-and-mouth disease virus (FMDV) consists of two distinct elements, a 90 nt untranslated region (3'-NCR) and a poly(A) tract. Removal of either the poly(A) tract or both the 3'-NCR and the poly(A) tract abrogated infectivity in susceptible cells in the context of a full-length cDNA clone. We have addressed the question of whether the impairment of RNA infectivity is related to defects at the translation level using a double approach. First, compared to the full-length viral RNA, removal of the 3' sequences reduced the efficiency of translation in vitro. Secondly, a stimulatory effect of the 3' end sequences on IRES-dependent translation was found in vivo using bicistronic constructs. RNAs carrying the FMDV 3' end sequences linked to the second cistron showed a significant stimulation of IRES-dependent translation, whereas cap-dependent translation was not affected. Remarkably, IRES-dependent stimulation exerted by the poly(A) tract or the 3'-NCR seems to be the result of two separate events, as the 3'-NCR alone enhanced IRES activity on its own. Under conditions of FMDV Lb protease-induced translation shut-off, the stimulation of IRES activity reached values above 6-fold in living cells. A northern blot analysis indicated that IRES stimulation was not the consequence of a change in the stability of the bicistronic RNA produced in transfected cells. Analysis of the RNA-binding proteins interacting with a mixture of 3' end and IRES probes showed an additive pattern. Altogether, our results strongly suggest that individual signals in the viral 3' end ensure stimulation of FMDV translation.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: López de Quinto
authors.forename: Margarita
authors.initials: M
authors.lastname: Sáiz
authors.forename: Diana
authors.initials: D
authors.lastname: de la Morena
authors.forename: Francisco
authors.initials: F
authors.lastname: Sobrino
authors.forename: Encarnación
authors.initials: E
authors.lastname: Martínez-Salas
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D029544:Foot-and-Mouth Disease Virus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D011061:Poly A / Q000235:genetics*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012367:RNA, Viral / Q000096:biosynthesis* / Q000737:chemistry; D016601:RNA-Binding Proteins / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011061:Poly A