1AO0

GLUTAMINE PHOSPHORIBOSYLPYROPHOSPHATE (PRPP) AMIDOTRANSFERASE FROM B. SUBTILIS COMPLEXED WITH ADP AND GMP

Summary for 1AO0

• Entry DOI: 10.2210/pdb1ao0/pdb
• Descriptor: GLUTAMINE PHOSPHORIBOSYLPYROPHOSPHATE AMIDOTRANSFERASE, MAGNESIUM ION, IRON/SULFUR CLUSTER, ... (6 entities in total)
• Functional Keywords: transferase, glutamine amidotransferase, prtase, purine biosynthesis, phosphoribosyltransferase, glycosyltransferase
• Biological source: Bacillus subtilis
• Total number of polymer chains: 4
• Total formula weight: 204179.34

Authors

Tomchick, D.R.,Smith, J.L. (deposition date: 1997-07-15, release date: 1997-11-12, Last modification date: 2024-05-22)

Primary citation

Chen, S.,Tomchick, D.R.,Wolle, D.,Hu, P.,Smith, J.L.,Switzer, R.L.,Zalkin, H.
Mechanism of the synergistic end-product regulation of Bacillus subtilis glutamine phosphoribosylpyrophosphate amidotransferase by nucleotides.
Biochemistry, 36:10718-10726, 1997

PubMed Abstract: De novo purine nucleotide synthesis is regulated, at least in part, by end-product inhibition of glutamine PRPP amidotransferase. An important feature of this inhibition is the fact that certain synergistic nucleotide pairs give more than additive inhibition. The physiological importance of synergism is in amplifying regulation by the adenine and guanine nucleotide end products of de novo synthesis. Using a new method to quantitate synergism, ADP plus GMP were confirmed [Meyer, E., and Switzer, R. L. (1978) J. Biol. Chem. 254, 5397-5402] to give strong synergistic inhibition of Bacillus subtilis glutamine PRPP amidotransferase. An X-ray structure of the ternary enzyme.ADP.GMP complex established that ADP binds to the allosteric A site and GMP to the catalytic C site. GMP increased the binding affinity of ADP for the A site by approximately 20-fold. Synergism results from a specific nucleotide-nucleotide interaction that is dependent upon a nucleoside diphosphate in the A site and a nucleoside monophosphate in the C site. Furthermore, synergism is enhanced by the competition between nucleotide inhibitor and PRPP substrate for the C site. Purine base specificity results from a backbone carbonyl interaction of Lys305' with the 6-NH2 group of adenine in the A site and a Ser347 Ogamma interaction with the 2-NH2 group of guanine in the C site. Steric considerations favor binding of the nucleoside diphosphate to the A site. Site-directed replacements of key residues increased the nucleotide concentrations needed for 50% inhibition and in some cases perturbed synergism. Mutations in either of the nucleotide sites perturbed function at both sites, supporting the important role of synergism.

PubMed: 9271502
DOI: 10.1021/bi9711893

Experimental method

X-RAY DIFFRACTION (2.8 Å)