IS THERE METHYLMALONYL COA MUTASE IN ASPERGILLUS-NIDULANS

In most animal species and many prokaryotes, methylmalonyl CoA mutase catalyzes isomerization between methylmalonyl CoA and succinyl CoA using adenosylcobalamin as a cofactor. We describe the absence of this enzyme in Aspergillus nidulans based on the absence of enzyme activity in vitro and the failure to metabolize methylmalonate or grow in media containing this organic acid as the sole carbon source. These data contrast previous assumptions that propionate may be metabolized through propionyl CoA and methylmalonyl CoA to the TCA cycle in this organism. This is consistent with the separate evolution of these pathways in animals and lower eukaryotes due to the distinct endosymbiotic origin of their mitochondria. © 1991.