J. Bacteriol., Mar 1996, 1386-1393, Vol 178, No. 5
Copyright © 1996, American Society for Microbiology

Characterization of a glutathione-dependent formaldehyde dehydrogenase from Rhodobacter sphaeroides

RD Barber, MA Rott and TJ Donohue
Department of Bacteriology, University of Wisconsin-Madison 53706, USA.

Glutathione-dependent formaldehyde dehydrogenases (GSH-FDH) represent a ubiquitous class of enzymes, found in both prokaryotes and eukaryotes. During the course of studying energy-generating pathways in the photosynthetic bacterium Rhodobacter sphaeroides, a gene (adhI) encoding a GSH-FDH homolog has been identified as part of an operon (adhI-cycI) that also encodes an isoform of the cytochrome c2 family of electron transport proteins (isocytochrome c2). Enzyme assays with crude Escherichia coli extracts expressing AdhI show that this protein has the characteristic substrate preference of a GSH-FDH. Ferguson plot analysis with zymograms suggests that the functional form of AdhI is a homodimer of approximately40-kDa subunits, analogous to other GSH-FDH enzymes. These properties of AdhI were used to show that mutations which increase or decrease adhI expression change the specific activity of GSH-FDH in R. sphaeroides extracts. In addition, expression of the presumed adhI-cycI operon appears to be transcriptionally regulated, since the abundance of the major adhI-specific primer extension product is increased by the trans-acting spd-7 mutation, which increases the level of both isocytochrome c2 and AdhI activity. While transcriptional linkage of adhI and cycI could suggest a function in a common metabolic pathway, isocytochrome c2 (periplasm) and AdhI (cytoplasm) are localized in separate compartments of R. sphaeroides. Potential roles for AdhI in carbon and energy generation and the possible relationship of GSH-FDH activity to isocytochrome c2 will be discussed based on the commonly accepted physiological functions of GSH-FDH enzymes in prokaryotes and eukaryotes.

This article has been cited by other articles:

• Wilson, S. M., Gleisten, M. P., Donohue, T. J. (2008). Identification of proteins involved in formaldehyde metabolism by Rhodobacter sphaeroides. Microbiology 154: 296-305 [Abstract] [Full Text]  
• Hickman, J. W., Witthuhn, V. C. Jr., Dominguez, M., Donohue, T. J. (2004). Positive and Negative Transcriptional Regulators of Glutathione-Dependent Formaldehyde Metabolism. J. Bacteriol. 186: 7914-7925 [Abstract] [Full Text]  
• Goenrich, M., Bartoschek, S., Hagemeier, C. H., Griesinger, C., Vorholt, J. A. (2002). A Glutathione-dependent Formaldehyde-activating Enzyme (Gfa) from Paracoccus denitrificans Detected and Purified via Two-dimensional Proton Exchange NMR Spectroscopy. J. Biol. Chem. 277: 3069-3072 [Abstract] [Full Text]  
• Hickman, J. W., Barber, R. D., Skaar, E. P., Donohue, T. J. (2002). Link between the Membrane-Bound Pyridine Nucleotide Transhydrogenase and Glutathione-Dependent Processes in Rhodobacter sphaeroides. J. Bacteriol. 184: 400-409 [Abstract] [Full Text]  
• Echenique, J. R., Dorsey, C. W., Patrito, L. C., Petroni, A., Tolmasky, M. E., Actis, L. A. (2001). Acinetobacter baumannii has two genes encoding glutathione-dependent formaldehyde dehydrogenase: evidence for differential regulation in response to iron. Microbiology 147: 2805-2815 [Abstract] [Full Text]  
• Fernandez, M. R., Biosca, J. A., Torres, D., Crosas, B., Pares, X. (1999). A Double Residue Substitution in the Coenzyme-binding Site Accounts for the Different Kinetic Properties between Yeast and Human Formaldehyde Dehydrogenases. J. Biol. Chem. 274: 37869-37875 [Abstract] [Full Text]  
• Vorholt, J. A., Chistoserdova, L., Stolyar, S. M., Thauer, R. K., Lidstrom, M. E. (1999). Distribution of Tetrahydromethanopterin-Dependent Enzymes in Methylotrophic Bacteria and Phylogeny of Methenyl Tetrahydromethanopterin Cyclohydrolases. J. Bacteriol. 181: 5750-5757 [Abstract] [Full Text]  
• Karls, R. K., Brooks, J., Rossmeissl, P., Luedke, J., Donohue, T. J. (1998). Metabolic Roles of a Rhodobacter sphaeroides Member of the sigma 32 Family. J. Bacteriol. 180: 10-19 [Abstract] [Full Text]