Effects of common polymorphisms on the properties of recombinant human methylenetetrahydrofolate reductase.

Abstract

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of methylenetetrahydrofolate to methyltetrahydrofolate, the major methyl donor for the conversion of homocysteine to methionine. Two common polymorphisms of the human enzyme have been identified: 677C>T, which leads to the substitution of Ala-222 by valine, and 1298A>C, which leads to the replacement of Glu-429 by alanine; the former polymorphism is the most frequent genetic cause of mild hyperhomocysteinemia, a risk factor for cardiovascular disease. By using a baculovirus expression system, recombinant human MTHFR has been expressed at high levels and purified to homogeneity in quantities suitable for biochemical characterization. The Glu429Ala protein has biochemical properties that are indistinguishable from the wild-type enzyme. The Ala222Val MTHFR, however, has an enhanced propensity to dissociate into monomers and to lose its FAD cofactor on dilution; the resulting loss of activity is slowed in the presence of methyltetrahydrofolate or adenosylmethionine. This biochemical phenotype is in good agreement with predictions made on the basis of studies comparing wild-type Escherichia coli MTHFR with a mutant, Ala177Val, homologous to the Ala222Val mutant human enzyme [Guenther, B. D., et al. (1999) Nat. Struct. Biol. 6, 359-365].

• Authors: K Yamada, Z Chen, R Rozen, R G Matthews
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 98 Issue 26 Pg. 14853-8 (Dec 18 2001) ISSN: 0027-8424 [Print] United States
• PMID: 11742092 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Recombinant Proteins
• Flavin-Adenine Dinucleotide
• Oxidoreductases Acting on CH-NH Group Donors
• Methylenetetrahydrofolate Reductase (NADPH2)

Topics

• Animals
• Flavin-Adenine Dinucleotide (metabolism)
• Humans
• Kinetics
• Methylenetetrahydrofolate Reductase (NADPH2)
• Mutation
• Oxidoreductases Acting on CH-NH Group Donors (chemistry, genetics, isolation & purification, metabolism)
• Polymorphism, Genetic
• Recombinant Proteins (chemistry, genetics, isolation & purification, metabolism)