Acetyl-CoA carboxylase (ACCase), carboxyltransferase domain (plant homomeric) (ACCase-CT)

Acetyl-CoA carboxylase (ACCase) is a vital enzyme that catalyzes the first committed and rate-limiting step in fatty acid biosynthesis, specifically the ATP-dependent carboxylation of acetyl-CoA to form malonyl-CoA (Sasaki & Nagano, 2004). In plants, the homomeric form of ACCase is a large, multifunctional polypeptide located in the cytosol of all plants and within the plastids of the Poaceae (grass) family (Délye, 2005). The carboxyltransferase (CT) domain of this homomeric enzyme serves as the specific molecular target for three major classes of herbicides: aryloxyphenoxypropionates (FOPs), cyclohexanediones (DIMs), and phenylpyrazolines (DENs) (Incledon & Hall, 1997). These herbicides, collectively known as graminicides, bind to the CT domain and prevent the transfer of the carboxyl group from biotin to acetyl-CoA (HRAC, 2024). This action depletes the pool of malonyl-CoA, halting the production of essential fatty acids and leading to the collapse of cell membranes and plant death (Sasaki & Nagano, 2004). The selectivity of these herbicides arises because most dicotyledonous plants utilize a herbicide-insensitive heteromeric ACCase in their plastids (Délye, 2005). However, the efficacy of these treatments is increasingly challenged by the emergence of herbicide-resistant weed populations, often driven by specific point mutations within the CT domain that disrupt drug binding (Délye, 2005).

Other names

Homomeric acetyl-CoA carboxylasePlastidial homomeric ACCaseCT domain of ACCaseACC1ACC2

Inhibition of the carboxyltransferase activity of the homomeric acetyl-CoA carboxylase enzyme, preventing the conversion of acetyl-CoA to malonyl-CoA and thereby halting de novo fatty acid biosynthesis.