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Crystal structure of a purine/pyrimidine phosphoribosyltransferase‐related protein from Thermus thermophilus HB8
Author(s) -
Rehse Peter H.,
Tahirov Tahir H.
Publication year - 2005
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20624
Subject(s) - thermus thermophilus , adenine phosphoribosyltransferase , dimer , crystallography , phosphoribosyltransferase , chemistry , pyrimidine , stereochemistry , active site , monomer , crystal structure , purine , enzyme , biochemistry , hypoxanthine guanine phosphoribosyltransferase , escherichia coli , organic chemistry , polymer , mutant , gene
Adenine phosphoribosyltransferase (APRTase) is a widely distributed enzyme involved in the salvage of adenine to form an adenine nucleotide. We crystallized and determined the X‐ray crystallographic structure of a purine/pyrimidine phosphoribosyltransferase‐related protein from the thermophilic bacterium, Thermus thermophilus HB8. The crystal space group was C2 with unit cell dimensions of a = 167.42 Å, b = 61.41 Å, c = 102.39 Å, β = 94.0°. Initial phases were determined to 2.6 Å using the multiple wavelength anomalous dispersion method and selenomethionine substituted protein (Se‐MAD), and refined using a 1.9 Å “native” data set. The asymmetric unit contains two pairs of identical dimers, each related by noncrystallographic two‐fold symmetry. The fifth monomer forms a similar dimer across a crystallographic two‐fold axis. These dimers appear to be the biological unit with both monomers contributing to an unusual highly charged arginine‐rich bridge region separating the two active sites. Comparison with distantly related APRTases reveal similarities and differences of the active site. Proteins 2005. © 2005 Wiley‐Liss, Inc.