Steve Ealick's Research Group

Bacillus cereus Adenosine Phosphorylase

PDB files:

3UAV native with SO4

3UAW native with adenosine and SO4

3UAX native with inosine and SO4

3UAY D204N mutant with adenosine and SO4

3UAZ D204N mutant with inosine and SO4


Purine nucleoside phosphorylases catalyze the phosphorolytic cleavage of the glycosidic bond of purine (2-deoxy)nucleosides, generating the corresponding free base and (2-deoxy)- ribose 1-phosphate. Two classes of PNPs have been identified: homotrimers specific for 6-oxopurines and homohexamers that accept both 6-oxopurines and 6-aminopurines. Bacillus cereus adenosine phosphorylase (AdoP) is a hexameric PNP similar to Escherichia coli PNPand Sulfolobus solfataricus 5′-deoxy-5′-methylthioadenosine phosphorylases (SsMTAP I and SsMTAP II); however, it is highly specific for 6-aminopurines.

The B. cereus AdoP protomer has the characteristic NP-I fold consisting of a single α/β-domain with a central nine-stranded β-sheet forming a distorted β-barrel that is surrounded by seven α-helices

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B. cereus AdoP was determined to be P6322 with one protomer per asymmetric unit. The hexamer has 32 symmetry and can be thought of as a trimer of dimers. Each dimer contains a pair of twofold-related active sites.


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The active site is located at the C-terminal end of the β-barrel and can be divided into three regions: the phosphate-binding site, the ribose-binding site and the base-binding site

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Dessanti P, Zhang Y, Allegrini S, Tozzi MG, Sgarrella F, and Ealick SE. Structural basis of the substrate specificity of Bacillus cereus adenosine phosphorylase. Acta Crystallogr. D 68:239-248 (2012).

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