title: Crystal structure of Arabidopsis thaliana Dawdle forkhead-associated domain reveals a conserved phospho-threonine recognition cleft for dicer-like 1 binding.
abstract: Dawdle (DDL) is a microRNA processing protein essential for the development of Arabidopsis. DDL contains a putative nuclear localization signal at its amino-terminus and forkhead-associated (FHA) domain at the carboxyl-terminus. Here, we report the crystal structure of the FHA domain of Arabidopsis Dawdle, determined by multiple-wavelength anomalous dispersion method at 1.7-Å resolution. DDL FHA structure displays a seven-stranded β-sandwich architecture that contains a unique structural motif comprising two long anti-parallel strands. Strikingly, crystal packing of the DDL FHA domain reveals that a glutamate residue from the symmetry-related DDL FHA domain, a structural mimic of the phospho-threonine, is specifically recognized by the structurally conserved phospho-threonine binding cleft. Consistently with the structural observations, co-immuno-precipitation experiments performed in Nicotiana benthamiana show that the DDL FHA domain co-immuno-precipitates with DCL1 fragments containing the predicted pThr+3(Ile/Val/Leu/Asp) motif. Taken together, we count the recognition of the target residue by the canonical binding cleft of the DDL FHA domain as the key molecular event to instate FHA domain-mediated protein-protein interaction in plant miRNA processing.
authors: Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
authors: Satoru
authors: S
authors: Machida
authors: Y Adam
authors: YA
authors: Yuan
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D035683:MicroRNAs / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010769:Phosphothreonine / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012323:RNA Processing, Post-Transcriptional; D043244:Ribonuclease III / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C514692:DAWDLE protein, Arabidopsis; D035683:MicroRNAs; D010769:Phosphothreonine; C402383:DCL1 protein, Arabidopsis; D043244:Ribonuclease III
keywords: Arabidopsis DCL1; Arabidopsis DDL; forkhead-associated domain; microRNA processing.; phospho-threonine