title: Crystal Structure of the N-Terminal RNA Recognition Motif of mRNA Decay Regulator AUF1.
abstract: AU-rich element binding/degradation factor 1 (AUF1) plays a role in destabilizing mRNAs by forming complexes with AU-rich elements (ARE) in the 3'-untranslated regions. Multiple AUF1-ARE complexes regulate the translation of encoded products related to the cell cycle, apoptosis, and inflammation. AUF1 contains two tandem RNA recognition motifs (RRM) and a Gln- (Q-) rich domain in their C-terminal region. To observe how the two RRMs are involved in recognizing ARE, we obtained the AUF1-p37 protein covering the two RRMs. However, only N-terminal RRM (RRM1) was crystallized and its structure was determined at 1.7 Å resolution. It appears that the RRM1 and RRM2 separated before crystallization. To demonstrate which factors affect the separate RRM1-2, we performed limited proteolysis using trypsin. The results indicated that the intact proteins were cleaved by unknown proteases that were associated with them prior to crystallization. In comparison with each of the monomers, the conformations of the β2-β3 loops were highly variable. Furthermore, a comparison with the RRM1-2 structures of HuR and hnRNP A1 revealed that a dimer of RRM1 could be one of the possible conformations of RRM1-2. Our data may provide a guidance for further structural investigations of AUF1 tandem RRM repeat and its mode of ARE binding.
authors.affiliation: Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Je-Hyun
authors.identifier: 0000-0001-7615-8654
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea.
authors.forename: Jeong Ho
authors.identifier: 0000-0002-2126-0317
authors.initials: JH
authors.lastname: Chang
mesh_terms: D020413:3' Untranslated Regions; D017209:Apoptosis; D018360:Crystallography, X-Ray; D000067780:ELAV-Like Protein 1 / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000737:chemistry* / Q000235:genetics*; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000737:chemistry; D006801:Humans; D007249:Inflammation; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D059748:Proteolysis; D020871:RNA Stability; D012260:Ribonucleases / Q000737:chemistry; D020080:Tandem Repeat Sequences
chemical_list: D020413:3' Untranslated Regions; D000067780:ELAV-Like Protein 1; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012260:Ribonucleases