This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
5wwz
From Proteopedia
Crystal structure of the KH2 domain of human RNA-binding E3 ubiquitin-protein ligase MEX-3C
Structural highlights
DiseaseMEX3C_HUMAN Genetic variations in MEX3C may be associated with susceptibility to essential hypertension.[1] FunctionMEX3C_HUMAN E3 ubiquitin ligase responsible for the post-transcriptional regulation of common HLA-A allotypes. Binds to the 3' UTR of HLA-A2 mRNA, and regulates its levels by promoting mRNA decay. RNA binding is sufficient to prevent translation, but ubiquitin ligase activity is required for mRNA degradation.[2] [3] Publication Abstract from PubMedMEX-3 is a KH domain-containing RNA-binding protein, first identified as a translational repressor in Caenorhabditis elegans, while its four orthologs (MEX-3A-D) in human and mouse were subsequently found to have E3 ubiquitin ligase activity mediated by a RING domain and critical for RNA degradation. Current evidence implicates human MEX-3C in many essential biological processes and suggests a strong connection with immune diseases and carcinogenesis. The highly conserved dual KH domains in MEX-3 proteins enable RNA binding and are essential for the recognition of the 3' UTR and posttranscriptional regulation of MEX-3 target transcripts. However, the molecular mechanisms of translational repression and the consensus RNA sequence recognized by the MEX-3C KH domain are unknown. Here, using X-ray crystallography and isothermal titration calorimetry, we investigated the RNA-binding activity and selectivity of human MEX-3C dual KH domains. Our high-resolution crystal structures of individual KH domains complexed with a noncanonical U-rich and a GA-rich RNA sequences revealed that the KH1/2 domains of hMEX-3C bound MRE10, a 10-mer RNA (5'-CAGAGUUUAG-3') consisting of an eight-nucleotide MEX-3-recognition element (MRE) motif, with high affinity. Of note, we also identified a consensus RNA motif recognized by human MEX-3C. The potential RNA-binding sites in the 3' UTR of the human leukocyte antigen serotype (HLA-A2) mRNA were mapped with this RNA-binding motif and were further confirmed by fluorescence polarization. The binding motif identified here will provide valuable information for future investigations of the functional pathways controlled by human MEX-3C and for predicting potential mRNAs regulated by this enzyme. The human RNA-binding protein and E3 ligase MEX-3C binds the MEX-3-recognition element (MRE) motif with high affinity.,Yang L, Wang C, Li F, Zhang J, Nayab A, Wu J, Shi Y, Gong Q J Biol Chem. 2017 Aug 14. pii: jbc.M117.797746. doi: 10.1074/jbc.M117.797746. PMID:28808060[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||||
Categories: Homo sapiens | Large Structures | Gong Q | Li F | Wang C | Yang L
