Peroxisomal acetate/butyrate--CoA ligase that is probably involved in the activation of exogenous acetate for entry into the glyoxylate cycle. May play a role to prevent carbon loss from peroxisomes during lipid mobilization. In vitro, is active with both acetate and butyrate. acetate + ATP + CoA = acetyl-CoA + AMP + diphosphate a medium chain fatty acid + ATP + CoA = a medium-chain fatty acyl-CoA + AMP + diphosphate Expressed in roots, leaves, stems, flowers and developing seeds. No visible phenotype under normal growth conditions, but seedlings have a strong decrease in glutamine and are resistant to the toxic acetate analog monofluoroacetic acid. Belongs to the ATP-dependent AMP-binding enzyme family.