title: A novel role for poly(C) binding proteins in programmed ribosomal frameshifting.
abstract: Translational control through programmed ribosomal frameshifting (PRF) is exploited widely by viruses and increasingly documented in cellular genes. Frameshifting is induced by mRNA secondary structures that compromise ribosome fidelity during decoding of a heptanucleotide 'slippery' sequence. The nsp2 PRF signal of porcine reproductive and respiratory syndrome virus is distinctive in directing both -2 and -1 PRF and in its requirement for a trans-acting protein factor, the viral replicase subunit nsp1β. Here we show that the the trans-activation of frameshifting is carried out by a protein complex composed of nsp1β and a cellular poly(C) binding protein (PCBP). From the results of in vitro translation and electrophoretic mobility shift assays, we demonstrate that a PCBP/nsp1β complex binds to a C-rich sequence downstream of the slippery sequence and here mimics the activity of a structured mRNA stimulator of PRF. This is the first description of a role for a trans-acting cellular protein in PRF. The discovery broadens the repertoire of activities associated with poly(C) binding proteins and prototypes a new class of virus-host interactions.
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
authors.forename: Sawsan
authors.initials: S
authors.lastname: Napthine
authors.affiliation: Department of Medical Microbiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
authors.forename: Emmely E
authors.initials: EE
authors.lastname: Treffers
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
authors.forename: Susanne
authors.initials: S
authors.lastname: Bell
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Goodfellow
authors.affiliation: College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5705, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK aef24@cam.ac.uk.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Firth
authors.affiliation: Department of Medical Microbiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands e.j.snijder@lumc.nl.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Snijder
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK ib103@mole.bio.cam.ac.uk.
authors.forename: Ian
authors.initials: I
authors.lastname: Brierley
mesh_terms: D000818:Animals; D001483:Base Sequence; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics*; D018965:Frameshifting, Ribosomal / Q000235:genetics*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics; D009690:Nucleic Acid Conformation; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000472:pathogenicity; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics; D012270:Ribosomes / Q000235:genetics*; D013552:Swine / Q000235:genetics / Q000821:virology
chemical_list: D046912:Multiprotein Complexes; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D003546:Cysteine Endopeptidases; C078306:nsP2 proteinase