6g2i
Filament of acetyl-CoA carboxylase and BRCT domains of BRCA1 (ACC-BRCT) at 5.9 A resolution
Structural highlights
DiseaseACACA_HUMAN Defects in ACACA are a cause of acetyl-CoA carboxylase 1 deficiency (ACACAD) [MIM:613933; also known as ACAC deficiency or ACC deficiency. An inborn error of de novo fatty acid synthesis associated with severe brain damage, persistent myopathy and poor growth.[1] FunctionACACA_HUMAN Catalyzes the rate-limiting reaction in the biogenesis of long-chain fatty acids. Carries out three functions: biotin carboxyl carrier protein, biotin carboxylase and carboxyltransferase.[2] Publication Abstract from PubMedAcetyl-CoA carboxylase catalyses the ATP-dependent carboxylation of acetyl-CoA, a rate-limiting step in fatty acid biosynthesis(1,2). Eukaryotic acetyl-CoA carboxylases are large, homodimeric multienzymes. Human acetyl-CoA carboxylase occurs in two isoforms: the metabolic, cytosolic ACC1, and ACC2, which is anchored to the outer mitochondrial membrane and controls fatty acid beta-oxidation(1,3). ACC1 is regulated by a complex interplay of phosphorylation, binding of allosteric regulators and protein-protein interactions, which is further linked to filament formation(1,4-8). These filaments were discovered in vitro and in vivo 50 years ago(7,9,10), but the structural basis of ACC1 polymerization and regulation remains unknown. Here, we identify distinct activated and inhibited ACC1 filament forms. We obtained cryo-electron microscopy structures of an activated filament that is allosterically induced by citrate (ACC-citrate), and an inactivated filament form that results from binding of the BRCT domains of the breast cancer type 1 susceptibility protein (BRCA1). While non-polymeric ACC1 is highly dynamic, filament formation locks ACC1 into different catalytically competent or incompetent conformational states. This unique mechanism of enzyme regulation via large-scale conformational changes observed in ACC1 has potential uses in engineering of switchable biosynthetic systems. Dissecting the regulation of acetyl-CoA carboxylase opens new paths towards counteracting upregulation of fatty acid biosynthesis in disease. Structural basis for regulation of human acetyl-CoA carboxylase.,Hunkeler M, Hagmann A, Stuttfeld E, Chami M, Guri Y, Stahlberg H, Maier T Nature. 2018 Jun 13. pii: 10.1038/s41586-018-0201-4. doi:, 10.1038/s41586-018-0201-4. PMID:29899443[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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