Formaldehyde dehydrogenase preparations from Methylococcus capsulatus (Bath) comprise methanol dehydrogenase and methylene tetrahydromethanopterin dehydrogenase.
In methylotrophic bacteria, formaldehyde is an important but potentially toxic metabolic intermediate that can be assimilated into biomass or oxidized to yield energy. Previously reported was the purification of an NAD(P)(+)-dependent formaldehyde dehydrogenase (FDH) from the obligate methane-oxidizing methylotroph Methylococcus capsulatus (Bath), presumably important in formaldehyde oxidation, which required a heat-stable factor (known as the modifin) for FDH activity. Here, the major protein component of this FDH preparation was shown by biophysical techniques to comprise subunits of 64 and 8 kDa in an alpha(2)beta(2) arrangement. N-terminal sequencing of the subunits of FDH, together with enzymological characterization, showed that the alpha(2)beta(2) tetramer was a quinoprotein methanol dehydrogenase of the type found in other methylotrophs. The FDH preparations were shown to contain a highly active NAD(P)(+)-dependent methylene tetrahydromethanopterin dehydrogenase that was the probable source of the NAD(P)(+)-dependent formaldehyde oxidation activity. These results support previous findings that methylotrophs possess multiple pathways for formaldehyde dissimilation.
Adeosun
Ekundayo K
EK
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Smith
Thomas J
TJ
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Hoberg
Anne-Mette
AM
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Velarde
Giles
G
Department of Biomolecular Sciences, PO Box 88, UMIST, Manchester M60 1QD, UK.
Ford
Robert
R
Department of Biomolecular Sciences, PO Box 88, UMIST, Manchester M60 1QD, UK.
Dalton
Howard
H
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D046911:Macromolecular Substances; D020619:Methylococcus capsulatus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid
D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D021122:Protein Subunits; D000429:Alcohol Oxidoreductases; C019641:alcohol dehydrogenase (acceptor); D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D000587:Oxidoreductases Acting on CH-NH Group Donors; C047126:methylenetetrahydromethanopterin dehydrogenase