2zi0
Crystal structure of Tav2b/siRNA complex
Structural highlights
Function2B_TAV Acts as suppressor of RNA-mediated gene silencing, also known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs. Forms a homodimer to measure siRNA duplex in a length-preferencemode. Binds to both siRNA duplexes (19bp) and long siRNA duplexes (30bp).[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 2b proteins encoded by cucumovirus act as post-transcriptional gene silencing suppressors to counter host defence during infection. Here we report the crystal structure of Tomato aspermy virus 2b (TAV2b) protein bound to a 19 bp small interfering RNA (siRNA) duplex. TAV2b adopts an all alpha-helix structure and forms a homodimer to measure siRNA duplex in a length-preference mode. TAV2b has a pair of hook-like structures to recognize simultaneously two alpha-helical turns of A-form RNA duplex by fitting its alpha-helix backbone into two adjacent major grooves of siRNA duplex. The conserved pi-stackings between tryptophan and the 5'-terminal base of siRNA duplex from both ends enhance the recognition. TAV2b further oligomerizes to form a dimer of dimers through the conserved leucine-zipper-like motif at its amino-terminal alpha-helix. Biochemical experiments suggest that TAV2b might interfere with the post-transcriptional gene silencing pathway by directly binding to siRNA duplex. Structural basis for RNA-silencing suppression by Tomato aspermy virus protein 2b.,Chen HY, Yang J, Lin C, Yuan YA EMBO Rep. 2008 Aug;9(8):754-60. Epub 2008 Jul 4. PMID:18600235[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also
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