Functional roles of the tetramer organization of malic enzyme.

ABSTRACT: Malic enzyme has a dimer of dimers quaternary structure in which the dimer interface associates more tightly than the tetramer interface. In addition, the enzyme has distinct active sites within each subunit. The mitochondrial NAD(P)(+)-dependent malic enzyme (m-NAD(P)-ME) isoform behaves cooperatively and allosterically and exhibits a quaternary structure in dimer-tetramer equilibrium. The cytosolic NADP(+)-dependent malic enzyme (c-NADP-ME) isoform is noncooperative and nonallosteric and exists as a stable tetramer. In this study, we analyze the essential factors governing the quaternary structure stability for human c-NADP-ME and m-NAD(P)-ME. Site-directed mutagenesis at the dimer and tetramer interfaces was employed to generate a series of dimers of c-NADP-ME and m-NAD(P)-ME. Size dist

SUBMITTER: Hsieh JY 

PROVIDER: S-EPMC2709377 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature