Crystal Structure of Arabidopsis thaliana Dawdle Forkhead-Associated Domain Reveals a Conserved Phospho-Threonine Recognition Cleft for Dicer-Like 1 Binding

• Published in: Molecular plant Vol. 6; no. 4; pp. 1290 - 1300
• Main Authors: Machida, Satoru, Yuan, Y. Adam
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.07.2013
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Arabidopsis - metabolism; Arabidopsis DCL1; Arabidopsis DDL; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell Cycle Proteins - metabolism; Conserved Sequence; Crystallography, X-Ray; Dicer酶; forkhead-associated domain; microRNA processing; MicroRNAs - metabolism; Models, Molecular; Molecular Sequence Data; phospho-threonine; Phosphothreonine - metabolism; Protein Binding; Protein Structure, Tertiary; Ribonuclease III - metabolism; RNA Processing, Post-Transcriptional; Sequence Alignment; 保守; 叉头; 拟南芥; 晶体结构; 特异性识别; 磷酸化; 苏氨酸; Arabidopsis DDL; Arabidopsis DCL1; phospho-threonine; forkhead-associated domain; microRNA processing
• ISSN: 1674-2052; 1752-9867
• DOI: 10.1093/mp/sst007

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-termi- nus. Here, we report the crystal structure of the FHA domain of Arabidopsis Dawdle, determined by multiple-wavelength anomalous dispersion method at 1.7-A resolution. DDL FHA structure displays a seven-stranded 13-sandwich architec- ture 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 benthami- ana show that the DDL FHA domain co-immuno-precipitates with DCL1 fragments containing the predicted pThr＋3（lle/ 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.