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| - | [[Image:2qsu.jpg|left|200px]] | |
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| - | {{Structure
| + | ==Structure of Arabidopsis thaliana 5'-Methylthioadenosine nucleosidase in apo form== |
| - | |PDB= 2qsu |SIZE=350|CAPTION= <scene name='initialview01'>2qsu</scene>, resolution 2.0Å
| + | <StructureSection load='2qsu' size='340' side='right'caption='[[2qsu]], [[Resolution|resolution]] 2.00Å' scene=''> |
| - | |SITE=
| + | == Structural highlights == |
| - | |LIGAND=
| + | <table><tr><td colspan='2'>[[2qsu]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QSU OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2QSU FirstGlance]. <br> |
| - | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Methylthioadenosine_nucleosidase Methylthioadenosine nucleosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.16 3.2.2.16] </span>
| + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2Å</td></tr> |
| - | |GENE= AT4g38800 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=3702 Arabidopsis thaliana])
| + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2qsu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qsu OCA], [https://pdbe.org/2qsu PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2qsu RCSB], [https://www.ebi.ac.uk/pdbsum/2qsu PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2qsu ProSAT]</span></td></tr> |
| - | |DOMAIN=<span class='plainlinks'>[http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?uid=COG0775 Pfs]</span>
| + | </table> |
| - | |RELATEDENTRY=[[1jys|1JYS]], [[1nc1|1NC1]], [[1nc3|1NC3]], [[2h8g|2H8G]], [[1z5p|1Z5P]], [[2qt9|2QT9]], [[2qtb|2QTB]]
| + | == Function == |
| - | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2qsu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qsu OCA], [http://www.ebi.ac.uk/pdbsum/2qsu PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=2qsu RCSB]</span>
| + | [https://www.uniprot.org/uniprot/MTN1_ARATH 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).<ref>PMID:17144895</ref> <ref>PMID:18342331</ref> <ref>PMID:20345605</ref> |
| - | }}
| + | == Evolutionary Conservation == |
| - | | + | [[Image:Consurf_key_small.gif|200px|right]] |
| - | '''Structure of Arabidopsis thaliana 5'-Methylthioadenosine nucleosidase in apo form'''
| + | Check<jmol> |
| - | | + | <jmolCheckbox> |
| - | | + | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qs/2qsu_consurf.spt"</scriptWhenChecked> |
| - | ==Overview== | + | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> |
| - | 5'-Methylthioadenosine (MTA)/S-adenosylhomocysteine (SAH) nucleosidase (MTAN) is essential for cellular metabolism and development in many bacterial species. While the enzyme is found in plants, plant MTANs appear to select for MTA preferentially, with little or no affinity for SAH. To understand what determines substrate specificity in this enzyme, MTAN homologues from Arabidopsis thaliana (AtMTAN1 and AtMTAN2, which are referred to as AtMTN1 and AtMTN2 in the plant literature) have been characterized kinetically. While both homologues hydrolyze MTA with comparable kinetic parameters, only AtMTAN2 shows activity towards SAH. AtMTAN2 also has higher catalytic activity towards other substrate analogues with longer 5'-substituents. The structures of apo AtMTAN1 and its complexes with the substrate- and transition-state-analogues, 5'-methylthiotubercidin and formycin A, respectively, have been determined at 2.0-1.8 A resolution. A homology model of AtMTAN2 was generated using the AtMTAN1 structures. Comparison of the AtMTAN1 and AtMTAN2 structures reveals that only three residues in the active site differ between the two enzymes. Our analysis suggests that two of these residues, Leu181/Met168 and Phe148/Leu135 in AtMTAN1/AtMTAN2, likely account for the divergence in specificity of the enzymes. Comparison of the AtMTAN1 and available Escherichia coli MTAN (EcMTAN) structures suggests that a combination of differences in the 5'-alkylthio binding region and reduced conformational flexibility in the AtMTAN1 active site likely contribute to its reduced efficiency in binding substrate analogues with longer 5'-substituents. In addition, in contrast to EcMTAN, the active site of AtMTAN1 remains solvated in its ligand-bound forms. As the apparent pK(a) of an amino acid depends on its local environment, the putative catalytic acid Asp225 in AtMTAN1 may not be protonated at physiological pH and this suggests the transition state of AtMTAN1, like human MTA phosphorylase and Streptococcus pneumoniae MTAN, may be different from that found in EcMTAN.
| + | <text>to colour the structure by Evolutionary Conservation</text> |
| - | | + | </jmolCheckbox> |
| - | ==About this Structure== | + | </jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2qsu ConSurf]. |
| - | 2QSU is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QSU OCA].
| + | <div style="clear:both"></div> |
| - | | + | == References == |
| - | ==Reference== | + | <references/> |
| - | Molecular Determinants of Substrate Specificity in Plant 5'-Methylthioadenosine Nucleosidases., Siu KK, Lee JE, Sufrin JR, Moffatt BA, McMillan M, Cornell KA, Isom C, Howell PL, J Mol Biol. 2008 Feb 8;. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18342331 18342331]
| + | __TOC__ |
| | + | </StructureSection> |
| | [[Category: Arabidopsis thaliana]] | | [[Category: Arabidopsis thaliana]] |
| - | [[Category: Methylthioadenosine nucleosidase]] | + | [[Category: Large Structures]] |
| - | [[Category: Single protein]]
| + | [[Category: Howell PL]] |
| - | [[Category: Howell, P L.]] | + | [[Category: Siu KKW]] |
| - | [[Category: Siu, K K.W.]] | + | |
| - | [[Category: 3-layer (a,b,a) sandwich]]
| + | |
| - | [[Category: hydrolase]]
| + | |
| - | [[Category: rossmann fold]]
| + | |
| - | | + | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Apr 2 11:58:20 2008''
| + | |
