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Oxidation-induced intramolecular disulfide bond inactivates mitogen-activated protein kinase kinase 6 by inhibiting

Yarui Diao1, Wei Liu, Catherine C L Wong

  • 1Department of Biochemistry, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China.

Proceedings of the National Academy of Sciences of the United States of America
|November 17, 2010
PubMed

Insights

Mitogen-activated protein kinase kinase 6 (MKK6), a key regulator of p38 MAPKs, is inactivated by oxidation via a unique disulfide bond mechanism. Its activity is restored by reducing agents, identifying MKK6 and related MAP2Ks as cellular redox sensors.

Area of Science:

  • Biochemistry
  • Cellular Biology
  • Enzymology

Background:

  • Mitogen-activated protein kinase kinase 6 (MKK6) is a crucial enzyme in the mitogen-activated protein kinase (MAPK) signaling pathway.
  • MKK6 specifically phosphorylates and activates p38 MAPKs, which are involved in various cellular responses.
  • Understanding the regulation of MKK6 activity is vital for comprehending cellular signaling under different conditions.

Purpose of the Study:

  • To investigate the sensitivity of MKK6 to oxidative stress.
  • To elucidate the molecular mechanism underlying MKK6 inactivation by oxidation.
  • To determine if this redox sensitivity is a conserved feature among related kinases.

Main Methods:

  • Biochemical assays to assess MKK6 kinase activity.
  • Cellular assays to evaluate MKK6 function in a cellular context.
  • Mechanistic studies to identify specific amino acid residues involved in redox regulation.
  • Comparative analysis of MKK6 with other members of the MAP2K family.

Main Results:

  • MKK6 kinase activity is significantly inhibited by oxidation and fully restored by reducing agents.
  • Oxidation leads to the formation of an intramolecular disulfide bond between Cysteines 109 and 196 in MKK6.
  • This disulfide bond formation inhibits MKK6 activity by blocking ATP binding, a novel mechanism for redox-sensitive kinases.
  • Conserved cysteines in other MAP2K family members suggest widespread redox sensitivity.

Conclusions:

  • MKK6 is highly sensitive to oxidation, with a unique mechanism of inactivation involving disulfide bond formation.
  • This redox regulation impacts MKK6's ability to bind ATP and phosphorylate its substrates.
  • MKK6 and other MAP2Ks represent a distinct class of cellular redox sensors, integrating oxidative signals into MAPK pathways.

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