Genomes and Genes
Control of cap-independent translation by a viral 3' UTR
Principal Investigator: WYATT ALLEN MILLER
Affiliation: Iowa State University
Abstract: All viruses must take over the host's protein synthesis (translation) machinery. Cellular mRNAs require a 5' cap and poly(A) tail to recruit the ribosome and initiate translation in a regulated manner. Many viral RNAs avoid this control step, and avoid host defenses, by lacking a 5' cap or poly(A) tail. Instead, many viral mRNAs harbor sequences in the untranslated regions (UTRs) that facilitate highly efficient cap-independent translation. Understanding how viruses do this could lead to development of antiviral agents that specifically target unique viral translation mechanisms. This knowledge could also allow exploitation of viruses as gene therapy vectors in humans, or as expression vectors to produce custom pharmaceutical polypeptides in plants. This proposal focuses on the novel cap-independent translation element (BTE) in the 3' UTR of barley yellow dwarf (BYDV) and other viral RNAs that facilitates translation initiation at the 5' end of the RNA. This process requires long-distance base pairing between the 5' and 3' UTRs. Our goal is to determine how the BTE recruits the translational machinery. In Aim I we will determine the sequence and structural requirements of the BTE at high resolution by high volume mutagenesis, and translation in cell-free wheat germ extracts and in plant protoplasts. In Aim II we will dissect the role and structural requirements of translation initiation factors eIF4G and eIF4E, and possibly other factors that are required for BTE-mediated translation. We will observe binding of mutant factors with the BTE RNA by a variety of RNA-protein interaction assays. The functions of mutant factors will be discerned by reconstituting factor-depleted cell-free extracts, and in cells depleted of factors by virus-induced gene silencing. In Aim III, the mechanism of ribosome entry on the RNA will be investigated by sucrose gradient centrifugation of RNA-ribosome complexes, toeprinting, and other approaches. Throughout the project, the role of the BTE and its interactors in virus replication will be assessed. This research on a model virus and major plant pathogen may contribute to understanding picornaviruses (e.g. polio) that also employ cap-independent translation regulated by interactions between the UTRs, and nidoviruses (e.g. SARS) and flaviviruses (e.g. dengue, West Nile) that regulate gene expression and replication by long-distance RNA base pairing. Finally, the research will provide fundamental insight on eukaryotic translation mechanisms. PUBLIC HEALTH RELEVANCE: All viruses must take over the host's protein synthesis (translation) machinery. Viruses of plants and animals share many common mechanisms for translation. We are using a plant virus as a small, easy-to-use model to investigate the mechanisms by which an RNA virus interacts with the host translational apparatus. This research may contribute to understanding mechanisms by which medically important viruses such as poliovirus, common cold rhinoviruses, the SARS virus, dengue virus, and West Nile viruses regulate gene expression and replication. Finally, the research will provide fundamental insight on translation mechanisms in cells of all higher organisms.
Funding Period: 2009-08-17 - 2011-07-31
more information: NIH RePORT
- Cap-independent translation of plant viral RNAsElizabeth L Pettit Kneller
Interdepartmental Plant Physiology Program, Department of Plant Pathology, 351 Bessey Hall, Iowa State University, Ames, IA 50011, USA
Virus Res 119:63-75. 2006..Much remains to be learned about how these elements enable plant viruses to usurp the host translational machinery...
- Translational control in positive strand RNA plant virusesTheo W Dreher
Department of Microbiology and Center for Gene Research and Biotechnology, 220 Nash Hall, Oregon State University, Corvallis, OR 97331, USA
Virology 344:185-97. 2006..Finally, future directions for research on the translation of plant positive strand viruses are discussed...
- Long-distance RNA-RNA interactions in plant virus gene expression and replicationW Allen Miller
Plant Pathology Department, Iowa State University, Ames, Iowa 50011, USA
Annu Rev Phytopathol 44:447-67. 2006..We emphasize viruses in the Tombusviridae and Luteoviridae families in which long-distance interactions are best characterized, but similar phenomena in other viruses are also discussed. Many more examples likely remain undiscovered...
- Oscillating kissing stem-loop interactions mediate 5' scanning-dependent translation by a viral 3'-cap-independent translation elementAurelie M Rakotondrafara
Molecular, Cellular, and Developmental Biology Program and Plant Pathology Department, Iowa State University, Ames, Iowa 50011, USA
RNA 12:1893-906. 2006..We propose that the kissing interaction is repeatedly disrupted by the scanning ribosome and re-formed in an oscillating process that regulates ribosome entry on the RNA...
- trans regulation of cap-independent translation by a viral subgenomic RNARuizhong Shen
Plant Pathology Department, 351 Bessey Hall, Iowa State University, Ames, IA 50011, USA
J Virol 80:10045-54. 2006..These results reveal (i) a new level of control of subgenomic-RNA gene expression, (ii) a new role for a viral subgenomic RNA, and (iii) a new mechanism for RNA-mediated regulation of translation...
- Structures required for poly(A) tail-independent translation overlap with, but are distinct from, cap-independent translation and RNA replication signals at the 3' end of Tobacco necrosis virus RNARuizhong Shen
Interdepartmental Genetics Program and Department of Plant Pathology, Iowa State University, IA 50011, USA
Virology 358:448-58. 2007..This work shows that a viral genome can harbor distinct cap- and poly(A) tail-mimic sequences in the 3' UTR...
- An overlapping essential gene in the PotyviridaeBetty Y W Chung
Biosciences Institute, University College Cork, Cork, Ireland
Proc Natl Acad Sci U S A 105:5897-902. 2008....
- Structure of a viral cap-independent translation element that functions via high affinity binding to the eIF4E subunit of eIF4FZhaohui Wang
Department of Plant Pathology and Biochemistry, Iowa State University, Ames, Iowa 50011, USA
J Biol Chem 284:14189-202. 2009..We conclude that the PTE recruits eIF4F by binding eIF4E. The PTE represents a different class of translation enhancer element, as defined by its structure and ability to bind eIF4E in the absence of an m(7)G cap...