Question

The metabolic fate of fatty acids is dependent on two enzymes, carnitine acyltransferase i and acetyl-coa carboxylase. carnitine acyltransferase i facilitates the transport of fatty acids to the mitochondria for β oxidation, whereas acetyl-coa carboxylase catalyzes the first reaction in the fatty acid synthesis pathway. the amp-activated protein kinase (ampk) regulates the activity of acetyl-coa carboxylase by phosphorylating a specific serine residue. mutation of this regulatory serine to alanine or aspartate would be expected to have different effects on the regulation of acetyl-coa carboxylase. select the statements that describe the expected effects of mutations of the regulatory serine.

Answer 1

The correct answer is the last statement.

If the regulatory serine is mutated to alanine, then acetyl-CoA carboxylase will get activated spontaneously and will produce malonyl-CoA. The increased concentrations of malonyl-CoA will obstruct the oxidation of fatty acids by preventing the entry of fatty acids into the mitochondria.

It is because the AMP-activated protein kinase phosphorylates the serine residues of acetyl-CoA carboxylase to inactivate it. If a mutation occurs in such residues, then the AMPL cannot phosphorylate acetyl-CoA carboxylase and this enzyme will get activated spontaneously.

In such a situation, there will be more than sufficient production of malonyl-CoA, which will inhibit the admittance of more fatty acid getting inside the mitochondria; this will indirectly prevent the oxidation of fatty acids.