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Structure of human DcpsStructure of human Dcps
Structural highlights
FunctionDCPS_HUMAN Decapping scavenger enzyme that catalyzes the cleavage of a residual cap structure following the degradation of mRNAs by the 3'->5' exosome-mediated mRNA decay pathway. Hydrolyzes cap analog structures like 7-methylguanosine nucleoside triphosphate (m7GpppG) with up to 10 nucleotide substrates (small capped oligoribonucleotides) and specifically releases 5'-phosphorylated RNA fragments and 7-methylguanosine monophosphate (m7GMP). Cleaves cap analog structures like tri-methyl guanosine nucleoside triphosphate (m3(2,2,7)GpppG) with very poor efficiency. Does not hydrolyze unmethylated cap analog (GpppG) and shows no decapping activity on intact m7GpppG-capped mRNA molecules longer than 25 nucleotides. Does not hydrolyze 7-methylguanosine diphosphate (m7GDP) to m7GMP (PubMed:22985415). May also play a role in the 5'->3 mRNA decay pathway; m7GDP, the downstream product released by the 5'->3' mRNA mediated decapping activity, may be also converted by DCPS to m7GMP (PubMed:14523240). Binds to m7GpppG and strongly to m7GDP. Plays a role in first intron splicing of pre-mRNAs. Inhibits activation-induced cell death.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedEukaryotic cells utilize DcpS, a scavenger decapping enzyme, to degrade the residual cap structure following 3'-5' mRNA decay, thereby preventing the premature decapping of the capped long mRNA and misincorporation of methylated nucleotides in nucleic acids. We report the structures of DcpS in ligand-free form and in a complex with m7GDP. apo-DcpS is a symmetric dimer, strikingly different from the asymmetric dimer observed in the structures of DcpS with bound cap analogues. In contrast, and similar to the m7GpppG-DcpS complex, DcpS with bound m7GDP is an asymmetric dimer in which the closed state appears to be the substrate-bound complex, whereas the open state mimics the product-bound complex. Comparisons of these structures revealed conformational changes of both the N-terminal swapped-dimeric domain and the cap-binding pocket upon cap binding. Moreover, Tyr273 in the cap-binding pocket displays remarkable conformational changes upon cap binding. Mutagenesis and biochemical analysis suggest that Tyr273 seems to play an important role in cap binding and product release. Examination of the crystallographic B-factors indicates that the N-terminal domain in apo-DcpS is inherently flexible, and in a dynamic state ready for substrate binding and product release. Crystal structures of human DcpS in ligand-free and m7GDP-bound forms suggest a dynamic mechanism for scavenger mRNA decapping.,Chen N, Walsh MA, Liu Y, Parker R, Song H J Mol Biol. 2005 Apr 8;347(4):707-18. PMID:15769464[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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