Two Aspergillus nidulans genes encoding methylenetetrahydrofolate reductases are up-regulated by homocysteine.
Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate in the synthesis of methionine from homocysteine. We have cloned and characterized two Aspergillus nidulans genes encoding MTHFRs: metA and metF. Mutations in either gene result in methionine requirement; the metA-encoded enzyme is responsible for only 10-15% of total MTHFR activity. These two enzymes belong to different classes of MTHFRs. Mutations in metA but not in the metF gene are suppressed by mutations resulting in enhancement of homocysteine synthesis. The expression of both genes is up-regulated by homocysteine.
Sieńko
Marzena
M
Institute of Biochemistry and Biophysics, PAS, Department of Genetics, 5A Pawińskiego Str, 02-106 Warszawa, Poland. marsi@ibb.waw.pl
Natorff
Renata
R
Zieliński
Zbigniew
Z
Hejduk
Arkadiusz
A
Paszewski
Andrzej
A
D001233:Aspergillus nidulans / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006710:Homocysteine; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008969:Molecular Sequence Data; D015854:Up-Regulation
D006710:Homocysteine; D042965:Methylenetetrahydrofolate Reductase (NADPH2)