The structure of class I N-deoxyribosyltransferase from Lactobacillus helveticus was determined by X-ray crystallography. Unlike class II N-deoxyribosyltransferases, which accept either purine or pyrimidine deoxynucleosides, class I enzymes are specific for purines as both the donor and acceptor base. Both class I and class II enzymes are highly specific for deoxynucleosides. The class I structure reveals similarities with the previously determined class II enzyme from Lactobacillus leichmanni [Armstrong, S. A., Cook, W. J., Short, S. A., and Ealick, S. E. (1996) Structure 4, 97-107]. The specificity of the class I enzyme for purine deoxynucleosides can be traced to a loop (residues 48-62), which shields the active site in the class II enzyme. In the class I enzyme, the purine base itself shields the active site from the solvent, while the smaller pyrimidine base cannot. The structure of the enzyme with a bound ribonucleoside shows that the nucleophilic oxygen atom of Glu101 hydrogen bonds to the O2' atom, rendering it unreactive and thus explaining the specificity for 2'-deoxynucleosides. The structure of a ribosylated enzyme intermediate reveals movements that occur during cleavage of the N-glycosidic bond. The structures of complexes with substrates and substrate analogues show that the purine base can bind in several different orientations, thus explaining the ability of the enzyme to catalyze alternate deoxyribosylation at the N3 or N7 position.
The line below this paragraph, {{ABSTRACT_PUBMED_14992575}}, adds the Publication Abstract to the page
(as it appears on PubMed at http://www.pubmed.gov), where 14992575 is the PubMed ID number.
-->
{{ABSTRACT_PUBMED_14992575}}
==About this Structure==
==About this Structure==
Line 29:
Line 33:
[[Category: Native]]
[[Category: Native]]
[[Category: Ptd]]
[[Category: Ptd]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:13:07 2008''
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 03:38:35 2008''
Revision as of 03:38, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
Structures of purine 2'-deoxyribosyltransferase, substrate complexes, and the ribosylated enzyme intermediate at 2.0 A resolution., Anand R, Kaminski PA, Ealick SE, Biochemistry. 2004 Mar 9;43(9):2384-93. PMID:14992575
