title: The CUG-initiated larger form coat protein of Chinese wheat mosaic virus binds to the cysteine-rich RNA silencing suppressor.
abstract: Some viruses use alternative translation initiation at non-AUG codons as a strategy to produce multiple proteins during gene expression. Here we show that, using this strategy, Chinese wheat mosaic virus (CWMV; Furovirus) expresses a larger form of coat protein (N-ext/CP) in infected plants. Site-directed mutagenesis and transient expression analysis confirmed that CWMV N-ext/CP is initiated at an upstream in-frame CUG codon at nucleotide position 207-209 of RNA 2, which adds a 39 amino acid (aa) N-terminal extension to the major CP. Interestingly, in planta and in vitro analyses indicated that CWMV N-ext/CP but not CP interacts with the CWMV cysteine-rich protein (CRP), an RNA silencing suppressor. We further determined that the N-terminal 39 aa extension, particularly the 10 aa region immediately upstream of the major CP coding region is responsible for the interaction of N-ext/CP with CRP. In an Agrobacterium co-infiltration assay, co-expression with N-ext/CP did not affect CRP silencing suppression activity. Thus the alternative translation initiation at a CUG codon provides the CWMV N-ext/CP with the ability to bind to the viral silencing suppressor.
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MoA Key Laboratory for Plant Protection and Biotechnology, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China.
authors.forename: Liying
authors.initials: L
authors.lastname: Sun
authors.forename: Ida Bagus
authors.initials: IB
authors.lastname: Andika
authors.forename: Jiangfeng
authors.initials: J
authors.lastname: Shen
authors.forename: Di
authors.initials: D
authors.lastname: Yang
authors.forename: Claudio
authors.initials: C
authors.lastname: Ratti
authors.forename: Jianping
authors.initials: J
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010442:Peptide Chain Initiation, Translational; D010935:Plant Diseases / Q000821:virology*; D011485:Protein Binding; D012328:RNA Viruses / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016415:Sequence Alignment; D013489:Suppression, Genetic; D014908:Triticum / Q000821:virology*
chemical_list: D036022:Capsid Proteins
keywords: Alternative translation initiation; CUG codon; Chinese wheat mosaic virus; Cysteine-rich suppressor; Furovirus; Larger form coat protein