Regulation of folate and one-carbon metabolism in mammalian cells. III. Role of mitochondrial folylpoly-gamma-glutamate synthetase

• Published in: The Journal of biological chemistry 1993-10, Vol.268 (29), p.21674-21679
• Main Authors: BI-FONG LIN, RWEI-FEN SUY HUANG, SHANE, B
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Carbon - metabolism; Cells, Cultured; CHO Cells; Cricetinae; Enzymes and enzyme inhibitors; Escherichia coli - enzymology; Folic Acid - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Kinetics; Miscellaneous; Mitochondria - enzymology; Peptide Synthases - metabolism; Subcellular Fractions - enzymology; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(20)80594-8

Wild-type Chinese hamster ovary (CHO) cells and CHO cell transfectants expressing human folylpoly-gamma-glutamate synthetase (FPGS) activity contain mitochondrial FPGS activity of higher specific activity than the cytosolic isozyme. Expression of mitochondrial FPGS activity is required for folate accumulation by mitochondria. The mitochondrial folate pool in CHO cells is not in equilibrium with the cytosolic pool and contains folylpolyglutamates of longer glutamate chain length than cytosolic folates. The inability of AUX-coli, a CHO cell expressing high levels of Escherichia coli FPGS activity and containing pteroyltriglutamate, to support glycine synthesis is due to a lack of mitochondrial FPGS activity. AUX-coli cells lack mitochondrial folate despite containing high levels of cytosolic folate.