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Sequestration‐mediated Downregulation of De Novo Purine Biosynthesis by AMPK
Author(s) -
Schmitt Danielle L,
An Songon
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.850.9
Subject(s) - ampk , purine , purine metabolism , biosynthesis , de novo synthesis , biochemistry , nucleotide salvage , downregulation and upregulation , enzyme , biology , microbiology and biotechnology , protein kinase a , chemistry , nucleotide , gene
Dynamic partitioning of de novo purine biosynthetic enzymes into multienzyme compartments has been associated with increased flux of de novo purine biosynthesis in human cells. However, we do not know of a mechanism by which de novo purine biosynthesis would be downregulated in cells. We speculated that AMP‐activated protein kinase (AMPK), which downregulates ATP‐consuming biosynthetic pathways of lipids and carbohydrates, would be a regulator for de novo purine biosynthesis. To understand the functional role of AMPK in the regulation of de novo purine biosynthesis, we have investigated the impact of small molecule‐mediated AMPK activation on de novo purine biosynthesis under fluorescence single‐cell microscopy. While monitoring the subcellular localizations of green fluorescent protein‐tagged pathway enzymes in HeLa cells, we identified that only one out of six pathway enzymes, formylglycinamidine ribonucleotide synthase (FGAMS), was found to associate into cytoplasmic granules, thus self‐assemblies, after treatment with small‐molecule AMPK activators. In addition, subsequent biochemical studies revealed that the cellular levels of purine metabolites were decreased, whereas the ATP levels were conserved upon stimulation of AMPK‐promoted FGAMS self‐assembly. Collectively, we demonstrate that downregulation of de novo purine biosynthesis is controlled by AMPK‐associated signaling pathways through the spatial sequestration of FGAMS into the self‐assembly. Support or Funding Information University of Maryland, Baltimore County and NIH/NIGMS T32GMO66706 (K. Radtke)