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Logo of jbcThe Journal of Biological Chemistry
 
J Biol Chem. 2015 March 13; 290(11): 6714.
PMCID: PMC4358095

Enzyme Clusters Enhance Metabolic Throughput♦

Quantitative Analysis of Purine Nucleotides Indicates That Purinosomes Increase de Novo Purine Biosynthesis

♦ See referenced article, J. Biol. Chem. 2015, 290, 6705–6713

Noncovalently bound complexes of enzymes involved in de novo purine synthesis, or purinosomes, have been observed, but the functional significance of these clusters is unknown. In this Paper of the Week, Stephen Benkovic's group at The Pennsylvania State University investigated the metabolic activity of purinosomes in vivo. The authors induced purinosome formation through purine starvation and then demonstrated that concentrations of purine nucleotide pools are elevated, not diminished, in purine-starved cells. Flux of the de novo purine synthesis pathway is elevated in these cells providing a potential explanation for increased nucleotide levels. Finally, the authors showed that purine starvation did not cause an increase in purinosome enzyme levels, but it did cause the enzymes that catalyze the rate-limiting steps in AMP and GMP synthesis to co-localize with purinosomes. The authors say, “The purinosome appears to be an example of ‘enzyme clustering’ to accelerate the processing of intermediates through metabolic channeling.”

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Rate-limiting enzymes in AMP and GMP formation co-localize with purinosomes in purine-starved cells.


Articles from The Journal of Biological Chemistry are provided here courtesy of American Society for Biochemistry and Molecular Biology