Studies on the Glutathione-Dependent Formaldehyde-Activating Enzyme from Paracoccus denitrificans

• Published in: PloS one Vol. 10; no. 12; p. e0145085
• Main Authors: Hopkinson, Richard J, Leung, Ivanhoe K H, Smart, Tristan J, Rose, Nathan R, Henry, Luc, Claridge, Timothy D W, Schofield, Christopher J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.12.2015; Public Library of Science (PLoS)
• Subjects: Alcohol; Amino Acid Sequence; Aqueous solutions; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Biochemistry; Carbon; Carbon-Sulfur Ligases - chemistry; Carbon-Sulfur Ligases - metabolism; Carcinogens; Catalysis; Chemistry; Dehydrogenases; Deoxyribonucleic acid; DNA; DNA repair; E coli; Enzymes; Escherichia coli; Formaldehyde; Formaldehyde-activating enzyme; Genetic aspects; Geometry; Glutathione; Glutathione - analogs & derivatives; Glutathione - metabolism; Iron; Laboratories; Mass spectrometry; Mass spectroscopy; Metabolism; Microbial metabolism; Molecular biology; Molecular Sequence Data; NMR; Nuclear magnetic resonance; Paracoccus denitrificans - enzymology; Physiological aspects; Pollutants; Proteins; RNA polymerase; Spectroscopy; Studies; United Kingdom; United Kingdom > UK
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0145085

Formaldehyde is a toxin and carcinogen that is both an environmental pollutant and an endogenous metabolite. Formaldehyde metabolism, which is probably essential for all aerobic cells, likely proceeds via multiple mechanisms, including via a glutathione-dependent pathway that is widely conserved in bacteria, plants and animals. However, it is unclear whether the first step in the glutathione-dependent pathway (i.e. formation of S-hydroxymethylglutathione (HMG)) is enzyme-catalysed. We report studies on glutathione-dependent formaldehyde-activating enzyme (GFA) from Paracoccus denitrificans, which has been proposed to catalyse HMG formation from glutathione and formaldehyde on the basis of studies using NMR exchange spectroscopy (EXSY). Although we were able to replicate the EXSY results, time course experiments unexpectedly imply that GFA does not catalyse HMG formation under standard conditions. However, GFA was observed to bind glutathione using NMR and mass spectrometry. Overall, the results reveal that GFA binds glutathione but does not directly catalyse HMG formation under standard conditions. Thus, it is possible that GFA acts as a glutathione carrier that acts to co-localise glutathione and formaldehyde in a cellular context.