Catalyzes the formation of acetyl phosphate from acetate and ATP. Can also catalyze the reverse reaction. Can also phosphorylate propionate, but has very low activity toward butyrate. acetate + ATP = acetyl phosphate + ADP Mg(2+). Can also accept Mn(2+). The Mg(2+) is bound between two conserved protein residues and the ATP phosphate groups. Inhibited by diethylpyrocarbonate, hydroxylamine and phenylglyoxal. Optimum temperature is 65 degrees Celsius. Protected from thermal inactivation by ATP. Metabolic intermediate biosynthesis; acetyl-CoA biosynthesis; acetyl-CoA from acetate: step 1/2. Homodimer. Belongs to the acetokinase family.