The aging-associated enzyme CLK-1 is a member of the carboxylate-bridged diiron family of proteins

Biochemistry. 2010 Nov 16;49(45):9679-81. doi: 10.1021/bi101475z. Epub 2010 Oct 21.


The aging-associated enzyme CLK-1 is proposed to be a member of the carboxylate-bridged diiron family of proteins. To evaluate this hypothesis and characterize the protein, we expressed soluble mouse CLK-1 (MCLK1) in Escherichia coli as a heterologous host. Using Mössbauer and EPR spectroscopy, we established that MCLK1 indeed belongs to this protein family. Biochemical analyses of the in vitro activity of MCLK1 with quinone substrates revealed that NADH can serve directly as a reductant for catalytic activation of dioxygen and substrate oxidation by the enzyme, with no requirement for an additional reductase protein component. The direct reaction of NADH with a diiron-containing oxidase enzyme has not previously been encountered for any member of the protein superfamily.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Dithionite / metabolism
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Kinetics
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mitochondrial Proteins / chemistry
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • Mixed Function Oxygenases
  • NAD / metabolism
  • Oxidation-Reduction
  • Oxygen / metabolism
  • Quinones / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Spectroscopy, Mossbauer
  • Substrate Specificity


  • Membrane Proteins
  • Mitochondrial Proteins
  • Quinones
  • Recombinant Proteins
  • NAD
  • Dithionite
  • Mixed Function Oxygenases
  • Coq7 protein, mouse
  • Oxygen