Identification of a denitrase activity against calmodulin in activated macrophages using high-field liquid chromatography--FTICR mass spectrometry.
We have identified a denitrase activity in macrophages that is upregulated following macrophage activation, which is shown by mass spectrometry to recognize nitrotyrosines in the calcium signaling protein calmodulin (CaM). The denitrase activity converts nitrotyrosines to their native tyrosine structure without the formation of any aminotyrosine. Comparable extents of methionine sulfoxide reduction are also observed that are catalyzed by endogenous methionine sulfoxide reductases. Competing with repair processes, oxidized CaM is a substrate for a peptidase activity that results in the selective cleavage of the C-terminal lysine (i.e., Lys148) that is expected to diminish CaM function. Thus, competing repair and peptidase activities define the abundances and functionality of CaM in modulating cellular metabolism in response to oxidative stress, where the presence of the truncated CaM species provides a useful biomarker for the transient appearance of oxidized CaM.
Smallwood
Heather S
HS
Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
Lourette
Natacha M
NM
Boschek
Curt B
CB
Bigelow
Diana J
DJ
Smith
Richard D
RD
Pasa-Tolić
Ljiljana
L
Squier
Thomas C
TC
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002645:Chickens; D002853:Chromatography, Liquid / Q000379:methods*; D008239:Lysine / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000201:enzymology*; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D010084:Oxidation-Reduction; D020033:Protein Isoforms / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry
D002147:Calmodulin; D020033:Protein Isoforms; C002744:3-nitrotyrosine; D014443:Tyrosine; D008239:Lysine