Catalyzes the oxidation of malonate semialdehyde (MSA) and methylmalonate semialdehyde (MMSA) into acetyl-CoA and propanoyl-CoA, respectively. 3-oxopropanoate + CoA + NAD(+) = acetyl-CoA + CO2 + NADH 2-methyl-3-oxopropanoate + CoA + H2O + NAD(+) = H(+) + hydrogencarbonate + NADH + propanoyl-CoA Polyol metabolism; myo-inositol degradation into acetyl-CoA; acetyl-CoA from myo-inositol: step 7/7. Homotetramer. Belongs to the aldehyde dehydrogenase family. IolA subfamily.