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This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 571/2/329    most recent jphysiol.2005.101089v2 jphysiol.2005.101089v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Santarelli, L. C. Articles by Hoshi, T. Search for Related Content PubMed PubMed Citation Articles by Santarelli, L. C. Articles by Hoshi, T. Related Collections Molecular and Genomic

¹ Department of Physiology
² Neuroscience Graduate Group, University of Pennsylvania, 3700 Hamilton Walk, Philadelphia, Pennsylvania 19104, USA
³ Molecular and Cellular Biophysics, Medical Faculty of the Friedrich Schiller University Jena, Drackendorfer Strasse 1, D-07747 Jena, Germany

Methionine-directed oxidation of the human Slo1 potassium channel (hSlo1) shifts the half-activation voltage by –30 mV and markedly slows channel deactivation at low concentrations of intracellular Ca²⁺ ([Ca²⁺]_i). We demonstrate here that the contemporaneous mutation of M536, M712 and M739 to leucine renders the channel functionally insensitive to methionine oxidation caused by the oxidant chloramine-T (Ch-T) without altering other functional characteristics. Coexpression with the auxiliary ß1 subunit fails to restore the full oxidative sensitivity to this triple mutant channel. The Ch-T effect is mediated specifically by M536, M712 and M739 because even small changes in this residue combination interfere with the ability to remove the oxidant sensitivity following mutation. Replacement of M712 or M739, but not M536, with the hydrophilic residue glutamate largely mimics oxidation of the channel and essentially removes the Ch-T sensitivity, suggesting that M712 and M739 may be part of a hydrophobic pocket disrupted by oxidation of non-polar methionine to the more hydrophilic methionine sulfoxide. The increase in wild-type hSlo1 open probability caused by methionine oxidation disappears at high [Ca²⁺]_i and biophysical modelling of the Ch-T effect on steady-state activation implicates a decrease in the allosteric coupling between Ca²⁺ binding and the pore. The dramatic increase in open probability at low [Ca²⁺]_i especially within the physiological voltage range suggests that oxidation of M536, M712 or M739 may enhance the Slo1 BK activity during conditions of oxidative stress, such as those associated with ischaemia-reperfusion and neurodegenerative disease, or in response to metabolic cues.

(Received 2 November 2005; accepted after revision 27 December 2005; first published online 5 January 2006)
Corresponding author T. Hoshi: Department of Physiology, University of Pennsylvania, 3700 Hamilton Walk, Philadelphia, PA 19104–6085, USA. Email: hoshi{at}hoshi.org

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