View source for 1jdv

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'''CRYSTAL STRUCTURE OF 5'-DEOXY-5'-METHYLTHIOADENOSINE PHOSPHORYLASE COMPLEXED WITH ADENOSINE AND SULFATE ION'''<br />

==Overview==
The structure of 5'-deoxy-5'-methylthioadenosine phosphorylase from, Sulfolobus solfataricus (SsMTAP) has been determined alone, as ternary, complexes with sulfate plus substrates 5'-deoxy-5'-methylthioadenosine, adenosine, or guanosine, or with the noncleavable substrate analog, Formycin B and as binary complexes with phosphate or sulfate alone. The, structure of unliganded SsMTAP was refined at 2.5-A resolution and the, structures of the complexes were refined at resolutions ranging from 1.6, to 2.0 A. SsMTAP is unusual both for its broad substrate specificity and, for its extreme thermal stability. The hexameric structure of SsMTAP is, similar to that of purine-nucleoside phosphorylase (PNP) from Escherichia, coli, however, only SsMTAP accepts 5'-deoxy-5'-methylthioadenosine as a, substrate. The active site of SsMTAP is similar to that of E. coli PNP, with 13 of 18 nearest residues being identical. The main differences are, at Thr(89), which corresponds to serine in E. coli PNP, and Glu(163), which corresponds to proline in E. coli PNP. In addition, a water molecule, is found near the purine N-7 position in the guanosine complex of SsMTAP., Thr(89) is near the 5'-position of the nucleoside and may account for the, ability of SsMTAP to accept either hydrophobic or hydrophilic substituents, in that position. Unlike E. coli PNP, the structures of SsMTAP reveal a, substrate-induced conformational change involving Glu(163). This residue, is located at the interface between subunits and swings in toward the, active site upon nucleoside binding. The high-resolution structures of, SsMTAP suggest that the transition state is stabilized in different ways, for 6-amino versus 6-oxo substrates. SsMTAP has optimal activity at 120, degrees C and retains full activity after 2 h at 100 degrees C., Examination of the three-dimensional structure of SsMTAP suggests that, unlike most thermophilic enzymes, disulfide linkages play a key in role in, its thermal stability.

==About this Structure==
1JDV is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sulfolobus_solfataricus Sulfolobus solfataricus] with SO4 and ADN as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/S-methyl-5-thioadenosine_phosphorylase S-methyl-5-thioadenosine phosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.28 2.4.2.28] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1JDV OCA]. 

==Reference==
Three-dimensional structure of a hyperthermophilic 5'-deoxy-5'-methylthioadenosine phosphorylase from Sulfolobus solfataricus., Appleby TC, Mathews II, Porcelli M, Cacciapuoti G, Ealick SE, J Biol Chem. 2001 Oct 19;276(42):39232-42. Epub 2001 Aug 6. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11489901 11489901]
[[Category: S-methyl-5-thioadenosine phosphorylase]]
[[Category: Single protein]]
[[Category: Sulfolobus solfataricus]]
[[Category: Appleby, T.C.]]
[[Category: Cacciapuoti, G.]]
[[Category: Ealick, S.E.]]
[[Category: Mathews, I.I.]]
[[Category: Porcelli, M.]]
[[Category: ADN]]
[[Category: SO4]]
[[Category: alpha-beta protein]]

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