Enables hydroxymethylglutaryl-CoA synthase activity. Predicted to be involved in acetyl-CoA metabolic process; farnesyl diphosphate biosynthetic process, mevalonate pathway; and ketone body biosynthetic process. Predicted to act upstream of or within cholesterol biosynthetic process. Located in mitochondrion. Is expressed in several structures, including alimentary system; cardiovascular system; facial bone primordium; nervous system; and reproductive system. Orthologous to human HMGCS2 (3-hydroxy-3-methylglutaryl-CoA synthase 2). [provided by Alliance of Genome Resources, Apr 2022]