title: Structure of the Arabidopsis thaliana DCL4 DUF283 domain reveals a noncanonical double-stranded RNA-binding fold for protein-protein interaction.
abstract: Dicer or Dicer-like (DCL) protein is a catalytic component involved in microRNA (miRNA) or small interference RNA (siRNA) processing pathway, whose fragment structures have been partially solved. However, the structure and function of the unique DUF283 domain within dicer is largely unknown. Here we report the first structure of the DUF283 domain from the Arabidopsis thaliana DCL4. The DUF283 domain adopts an alpha-beta-beta-beta-alpha topology and resembles the structural similarity to the double-stranded RNA-binding domain. Notably, the N-terminal alpha helix of DUF283 runs cross over the C-terminal alpha helix orthogonally, therefore, N- and C-termini of DUF283 are in close proximity. Biochemical analysis shows that the DUF283 domain of DCL4 displays weak dsRNA binding affinity and specifically binds to double-stranded RNA-binding domain 1 (dsRBD1) of Arabidopsis DRB4, whereas the DUF283 domain of DCL1 specifically binds to dsRBD2 of Arabidopsis HYL1. These data suggest a potential functional role of the Arabidopsis DUF283 domain in target selection in small RNA processing.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Haina
authors.initials: H
authors.lastname: Qin
authors.forename: Fading
authors.initials: F
authors.lastname: Chen
authors.forename: Xuelu
authors.initials: X
authors.lastname: Huan
authors.forename: Satoru
authors.initials: S
authors.lastname: Machida
authors.forename: Jianxing
authors.initials: J
authors.lastname: Song
authors.forename: Y Adam
authors.initials: YA
authors.lastname: Yuan
mesh_terms: D017360:Arabidopsis / Q000737:chemistry*; D001665:Binding Sites; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary; D012330:RNA, Double-Stranded / Q000737:chemistry; D043244:Ribonuclease III / Q000737:chemistry*
chemical_list: D012330:RNA, Double-Stranded; C504982:DCL4 protein, Arabidopsis; D043244:Ribonuclease III