FAMIN Is a Multifunctional Purine Enzyme Enabling the Purine Nucleotide Cycle.
Cader, M.Z., de Almeida Rodrigues, R.P., West, J.A., Sewell, G.W., Md-Ibrahim, M.N., Reikine, S., Sirago, G., Unger, L.W., Iglesias-Romero, A.B., Ramshorn, K., Haag, L.M., Saveljeva, S., Ebel, J.F., Rosenstiel, P., Kaneider, N.C., Lee, J.C., Lawley, T.D., Bradley, A., Dougan, G., Modis, Y., Griffin, J.L., Kaser, A.(2020) Cell 180: 278
- PubMed: 31978345 
- DOI: https://doi.org/10.1016/j.cell.2019.12.017
- Primary Citation of Related Structures:  
6T0Y, 6T1B - PubMed Abstract: 
Mutations in FAMIN cause arthritis and inflammatory bowel disease in early childhood, and a common genetic variant increases the risk for Crohn's disease and leprosy. We developed an unbiased liquid chromatography-mass spectrometry screen for enzymatic activity of this orphan protein. We report that FAMIN phosphorolytically cleaves adenosine into adenine and ribose-1-phosphate. Such activity was considered absent from eukaryotic metabolism. FAMIN and its prokaryotic orthologs additionally have adenosine deaminase, purine nucleoside phosphorylase, and S-methyl-5'-thioadenosine phosphorylase activity, hence, combine activities of the namesake enzymes of central purine metabolism. FAMIN enables in macrophages a purine nucleotide cycle (PNC) between adenosine and inosine monophosphate and adenylosuccinate, which consumes aspartate and releases fumarate in a manner involving fatty acid oxidation and ATP-citrate lyase activity. This macrophage PNC synchronizes mitochondrial activity with glycolysis by balancing electron transfer to mitochondria, thereby supporting glycolytic activity and promoting oxidative phosphorylation and mitochondrial H + and phosphate recycling.
Organizational Affiliation: 
Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.