This is a brief account of the scientific contribution of Professor Sir Howard Dalton FRS, who died in January 2008. It starts with his important study of the physiology of nitrogen-fixing bacteria, but concentrates on his work on methane oxidation. This started with the development of reliable assays for the methane monooxygenase, leading to the discovery of two types of enzyme, soluble and membrane-bound and their regulation by copper levels in the growth medium. His contribution to our understanding of the structure and function of these enzymes is then discussed and the review closes with a brief summary of our present knowledge of these important enzymes.
DaltonH., and PostgateJ.R. (1969) Effect of oxygen on growth of Azotobacter chroococcum in batch and continuous culture. J. Gen. Microbiol., 54, 463–473.
2.
DaltonH., and PostgateJ.R. (1969) Growth and physiology of Azotobacter chroococcum in continuous culture. J. Gen. Microbiol., 36, 307–319.
3.
DaltonH., MorrisJ.R., WardM.A., and MortensonL.E. (1971) Purification and some properties of molybdoferredoxin, a component of nitrogenase from Clostridium pasteurianum.Biochemistry, 10, 2066.
4.
DaltonH., and MortensonL.E. (1972) Dinitrogen (N2) fixation (with a Biochemical Emphasis). Bacteriol. Rev., 36, 231.
5.
DaltonH., and ZubietaJ. (1973) Ferredoxin from Veillonella alcalescens.Biochim. Biophys. Acta, 355, 133.
HansonR.S., and HansonT.E. (1996) Methanotrophic bacteria. Microbiol. Rev., 60, 439–471.
8.
DaltonH. (2005) The Leeuwenhoek Lecture 2000. The natural and unnatural history of methane-oxidising bacteria. Phil. Trans. R. Soc. B., 360, 1207–1222.
9.
HansenJ., SatoM., RuedyR., LacisA., and OinasV. (2000) Global warming in the twenty-first century: an alternative scenario. Proc. Natl Acad. Sci. USA, 97, 9875–9880.
10.
SmithT.J., and MurrellJ.C. (2008). Methanotrophs: biotechnological potential and emerging applications. In: FlickingerM.C. (ed.), The Encyclopedia of Industrial Biotechnology, Wiley (in press).
11.
WhittenburyR., PhillipsK.C., and WilkinsonJ.F. (1970) Enrichment, isolation and some properties of methane utilising bacteria. J. Gen. Microbiol., 61, 205–218.
12.
RibbonsD.W., and MichaloverJ.L. (1970) Methane oxidation by cell-free extracts of Methylococcus capsulatus.FEBS Lett., 11, 41–44.
13.
LeadbetterE.R., and FosterJ.W. (1959). Incorporation of molecular oxygen in bacterial cells utilizing hydrocarbons for growth. Nature, 184, 1428–1429.
14.
HigginsI.J., and QuayleJ.R. (1970) Oxygenation of methane by methane-grown Pseudomonas methanica and Methanomonas methanooxidans.Biochem. J., 118, 201–208.
15.
ColbyJ., DaltonH., and WhittenburyR. (1975) An improved assay for bacterial methane monooxygenase: some properties of the enzyme from Methylomonas methanica.Biochem. J., 151, 459–462.
16.
ColbyJ., StirlingD., and DaltonH. (1977) The soluble methane monooxygenase of Methylococcus capsulatus (Bath): its ability to oxygenate n-alkanes, n-alkenes, ethers, and acyclic, aromatic and heterocyclic compounds. Biochem. J., 165, 395–402.
17.
ColbyJ., and DaltonH. (1978) Resolution of the methane monooxygenase of Methylococcus capsulatus (Bath) into three components. Biochem. J., 171. 461–468.
18.
ColbyJ., and DaltonH. (1979) Characterisation of the second prosthetic group of the flavoenzyme NADH-acceptor reductase (component C) of the methane monooxygenase of Methylococcus capsulatus (Bath). Biochem. J., 177, 903–908.
19.
TongeG.M., HarrisonD.E.F., and HigginsI.J. (1977). Purification and properties of the methane monooxygenase system from Methylosinus trichosporium OB3b. Biochem. J., 161, 333–344.
20.
StanleyS.H., PriorS.D., LeakD.J., and DaltonH. (1983) Copper stress underlies the fundamental change in intracellular location of methane monooxygenase in methane-oxidising organisms: studies in batch and continuous cultures. Biotechnol. Lett., 5, 487–492.
21.
SmithD.D.S., and DaltonH. (1989) Solubilization of methane monooxygenase from Methylococcus capsulatus (Bath). Eur. J. Biochem., 182, 667–671.
22.
DaltonH. (1977) Ammonia oxidation by the methane oxidising bacterium Methylococcus capsulatus (Bath). Arch. Microbiol., 114, 273–279.
23.
DaltonH., and StirlingD.I. (1982) Co-metabolism. Phil. Trans. R. Soc. B, 297, 481–491.
24.
StirlingD.I., and DaltonH. (1979) The fortuitous oxidation and cometabolism of various carbon compounds by whole cell suspensions of Methylococcus capsulatus (Bath). FEMS Microbiol. Lett., 5, 315–318.
25.
RosenzweigA.C., FrederickC.A., LippardS.J., and NordlundP. (1993) Crystal Structure of a bacterial nonheme iron hydroxylase that catalyzes the biological oxidation of methane. Nature, 366, 537–543.
26.
GeorgeA.R., WilkinsP.C., and DaltonH. (1996) A computational investigation of the possible substrate binding sites in the hydroxylase of soluble methane monooxygenase. J. Mol. Catal. B, 2, 103–113.
27.
WaltersK.J., GassnerG.T., LippardS.J., and WagnerG. (1999) Structure of the soluble methane monooxygenase regulatory protein B. Proc. Natl. Acad. Sci. USA, 96, 7877–7882.
28.
NguyenH.H.T., ElliottS.J., YipJ.H.K., and ChanS.I. (1998) The particulate methane monooxygenase from Methylococcus capsulatus (Bath) is a novel copper-containing three-subunit enzyme–isolation and characterization. J. Biol. Chem., 273, 7957–7966.
29.
PriorS.D., and DaltonH. (1985) Acetylene as a suicide substrate and active site probe for methane mono-oxygenase from Methylococcus capsulatus (Bath). FEMS Lett., 29, 105–109.
30.
LiebermannR.L., and RosenzweigA.C. (2005) Crystal structure of a membrane-bound metalloenzyme that catalyses the biological oxidation of methane. Nature, 434, 177–182.
31.
KitmittoA., MyronovaN., BasuP., and DaltonH. (2005). Characterisation and structural analysis of an active particulate methane monooxygnease trimer form Methylococcus capsulatus (Bath). Biochemistry, 44, 10954–10965.
32.
WoodlandM.P., and DaltonH. (1984) Purification and characterization of component A of the methane monooxygenase from Methylococcus capsulatus (Bath). J. Biol. Chem., 259, 53–59.
33.
LundJ., and DaltonH. (1985) Further characterisation of the FAD and Fe2S2 redox centers of component C, the NADH: acceptor reductase of the soluble methane monooxygenase of Methylococcus capsulatus (Bath). Eur. J. Biochem., 147, 291–296.
34.
LundJ., WoodlandM.P., and DaltonH. (1985) Electron transfer reactions in the soluble methane monooxygenase of Methylococcus capsulatus (Bath). Eur. J. Biochem., 147, 297–305.
35.
DaltonH., WilkinsP.C., DeightonN., PodmoreI.D., and SymonsM.C. R. (1992) Electron paramagnetic resonance studies of the mechanism of substrate oxidation by methane monooxygenase. Faraday Discuss., 93, 163–171.
36.
MurreilJ.C., McDonaldI.R., and GilbertB. (2000) Regulation of expression of methane monooxygenases by copper ions. Trends Microbiol., 8, 221–225.
