3lgs

A. thaliana MTA nucleosidase in complex with S-adenosylhomocysteineA. thaliana MTA nucleosidase in complex with S-adenosylhomocysteine

Structural highlights 3lgs is a 4 chain structure with sequence from Arath. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: , , Related: 1jys, 1nc1, 2qtt, 2qtg, 2qsu, 2h8g, 1nc3 Gene: AT4g38800, atmtan1 (ARATH) Activity: Methylthioadenosine nucleosidase, with EC number 3.2.2.16 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [MTN1_ARATH] Enzyme of the methionine cycle that catalyzes the irreversible cleavage of the glycosidic bond in 5'-methylthioadenosine (MTA) to adenine and 5'-methylthioribose. Contributes to the maintenance of AdoMet homeostasis and is required to sustain high rates of ethylene synthesis. Inactive towards S-adenosylhomocysteine (SAH/AdoHcy). 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 PubMed 5'-Methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase (MTAN) plays a key role in the methionine-recycling pathway of bacteria and plants. Despite extensive structural and biochemical studies, the molecular mechanism of substrate specificity for MTAN remains an outstanding question. Bacterial MTANs show comparable efficiency in hydrolyzing MTA and SAH, while the plant enzymes select preferentially for MTA, with either no or significantly reduced activity towards SAH. Bacterial and plant MTANs show significant conservation in the overall structure, and the adenine- and ribose-binding sites. The observation of a more constricted 5'-alkylthio binding site in Arabidopsis thalianaAtMTAN1 and AtMTAN2, two plant MTAN homologues, led to the hypothesis that steric hindrance may play a role in substrate selection in plant MTANs. We show using isothermal titration calorimetry that SAH binds to both Escherichia coli MTAN (EcMTAN) and AtMTAN1 with comparable micromolar affinity. To understand why AtMTAN1 can bind but not hydrolyze SAH, we determined the structure of the protein-SAH complex at 2.2A resolution. The lack of catalytic activity appears to be related to the enzyme's inability to bind the substrate in a catalytically competent manner. The role of dynamics in substrate selection was also examined by probing the amide proton exchange rates of EcMTAN and AtMTAN1 via deuterium-hydrogen exchange coupled mass spectrometry. These results correlate with the B factors of available structures and the thermodynamic parameters associated with substrate binding, and suggest a higher level of conformational flexibility in the active site of EcMTAN. Our results implicate dynamics as an important factor in substrate selection in MTAN. Mechanism of substrate specificity in 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidases.,Siu KK, Asmus K, Zhang AN, Horvatin C, Li S, Liu T, Moffatt B, Woods VL Jr, Howell PL J Struct Biol. 2010 Jun 8. PMID:20554051 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

spinqualitylabelsall models 3lgs, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image