Molecular biology of cytosolic acetyl-CoA generation.
ATP citrate lyase (ACL) catalyses the ATP-dependent reaction between citrate and CoA to form oxaloacetate and acetyl-CoA. Our molecular characterizations of the cDNAs and genes coding for the Arabidopsis ACL indicate that the plant enzyme is heteromeric, consisting of two dissimilar subunits. The A subunit is homologous to the N-terminal third of the animal ACL, and the B subunit is homologous to C-terminal two-thirds of the animal ACL. Using both ACL-A- and ACL-B-specific antibodies and activity assays we have shown that ACL is located in the cytosol, and is not detectable in the plastids, mitochondria or peroxisomes. During seed development, ACL-A and ACL-B mRNA accumulation is co-ordinated with the accumulation of the cytosolic homomeric acetyl-CoA carboxylase mRNA. Antisense Arabidopsis plants reduced in ATP citrate lyase activity show a complex phenotype, with miniaturized organs, small cell size, aberrant plastid morphology and reduced cuticular wax. Our results indicate that ACL generates the cytosolic pool of acetyl-CoA, which is the substrate required for the biosynthesis of a variety of phytochemicals, including cuticular waxes and flavonoids.
Fatland
B
B
Department of Botany, Iowa State University, Ames, IA 50011, USA.
Anderson
M
M
Nikolau
B J
BJ
Wurtele
E S
ES
D001275:ATP Citrate (pro-S)-Lyase / Q000235:genetics* / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000096:biosynthesis / Q000378:metabolism*; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D003600:Cytosol / Q000201:enzymology; D008967:Molecular Biology / Q000379:methods; D030821:Plants, Genetically Modified / Q000201:enzymology; D021122:Protein Subunits; D012639:Seeds / Q000201:enzymology
D021122:Protein Subunits; D000105:Acetyl Coenzyme A; D001275:ATP Citrate (pro-S)-Lyase