Primary structure and activity of mouse methylmalonyl-CoA mutase

Abstract

Methylmalonyl-CoA mutase (MCM) is an adenosylcobalamin-dependent enzyme that catalyses isomerization between methylmalonyl-CoA and succinyl-CoA (3-carboxypropionyl-CoA). Genetic deficiency of this enzyme in man causes an often fatal disorder of organic acid metabolism termed mut methylmalonicacidaemia. We report cloning of a mouse MCM cDNA and the characterization of its primary structure and biological function. Mouse MCM in fibroblasts and crude liver extracts exhibits activity and reaction kinetics similar to those of the human enzyme. The predicted amino acid sequence of mouse MCM exhibits 94% identity with its human homologue and considerable identity with a prokaryotic MCM. Transfection of the mouse cDNA into cultured cells constitutes an active apoenzyme and can complement genetic deficiency of the apoenzyme in cells from patients with mut methylmalonicacidaemia. These results establish that mouse MCM is homologous to human MCM in structure and function and provides a basis for using the mouse as a model for studying this enzyme and its deficiency state.

Nitric Oxide Inhibits Mammalian Methylmalonyl-CoA Mutase

“…Thus, under conditions of relatively limited cobalamin availability, about threefourths of cellular methylmalonyl-CoA mutase was present as apoenzyme, and it could be converted to holoenzyme in vitro. Other workers have also found that the enzyme in vivo is largely in the apoenzyme form, including human skin and lung fibroblasts, human glioma cells, and human, mouse, and rat liver (26,27,(33)(34)(35). When cells were incubated for 16 h in DME medium containing 10% FBS supplemented with 1 M OH-Cbl, enzyme activity in the cell extracts increased to the same level as observed when extracts were incubated with AdoCbl ( Fig.…”

MeaB Is a Component of the Methylmalonyl-CoA Mutase Complex Required for Protection of the Enzyme from Inactivation

“…The P. shermanii and S. cinnamonensis MCM contain two homologous but non-identical subunits: ␣-subunit (ϳ79 kDa) and ␤-subunit (ϳ65 kDa) (7,8). The human (10), mouse (11), and E. coli (9) enzymes are homodimers. Crystal structures of P. shermanii MCM were determined (12,13) that revealed that both ␣ and ␤ subunits consist of two principal domains: an eight-stranded ␣/␤ triose phosphate isomerase barrel (␣/␤) 8 and a flavodoxin-like AdoCbl-binding fold.…”

“…Genes for MCM from Propionibacterium shermanii (7), Streptomyces cinnamonensis (8), Escherichia coli (9), humans (10), and mice (11) have been cloned and sequenced. The P. shermanii and S. cinnamonensis MCM contain two homologous but non-identical subunits: ␣-subunit (ϳ79 kDa) and ␤-subunit (ϳ65 kDa) (7,8).…”

Genetic and genomic systems to study methylmalonic acidemia

“…The mice prove that the pathway of propionyl-CoA metabolism operates in a manner similar to humans. The existence of a functionally equivalent pathway had been previously suspected based on homology between the mouse and human genes and the observation that the mouse gene could correct the propionate incorporation defect seen in human cells by transfection [56].…”