Linked Life Data

18076146

Source:http://linkedlifedata.com/resource/pubmed/id/18076146

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2008-1-2
pubmed:abstractText
The oxidation of methionines in calmodulin (CaM) can affect the activity of calcium pumps and channels to modulate the amplitude and duration of calcium signals. We have therefore investigated the possible oxidation of CaM in skeletal muscle and its effect on the CaM-dependent regulation of the RyR1 calcium release channel. Taking advantage of characteristic reductions in electrophoretic mobility determined by SDS-PAGE, we find that approximately two methionines are oxidized in CaM from skeletal muscle. The functional effect of CaM oxidation on the open probability of the RyR1 calcium release channel was assessed through measurements of [3H]ryanodine binding using a heavy sarcoplasmic reticulum preparation enriched in RyR1. There is a biphasic regulation of RyR1 by unoxidized CaM, in which calcium-activated CaM acts to enhance the calcium sensitivity of channel closure, while apo-CaM functions to enhance channel activity at resting calcium levels. We find that physiological levels of CaM oxidation preferentially weaken the CaM-dependent inhibition of the RyR1 calcium release channel observed at activating micromolar levels of calcium. In contrast, the oxidation of CaM resulted in minimal functional changes in the CaM-dependent activation of RyR1 at resting nanomolar calcium levels. Oxidation does not significantly affect the high-affinity binding of calcium-activated CaM to the CaM-binding sequence of RyR1; rather, methionine oxidation disrupts interdomain interactions between the opposing domains of CaM in complex with the CaM-binding sequence of RyR1 that normally function as part of a conformational switch associated with RyR1 inhibition. These results suggest that the oxidation of CaM can contribute to observed elevations in intracellular calcium levels in response to conditions of oxidative stress observed during biological aging. We suggest that the sensitivity of RyR1 channel activity to CaM oxidation may function as part of an adaptive cellular response that enhances the duration of calcium transients to promote enhanced contractility.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
47
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
131-42
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Loss of the calmodulin-dependent inhibition of the RyR1 calcium release channel upon oxidation of methionines in calmodulin.
pubmed:affiliation
Cell Biology and Biochemistry Group, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural