Covalent modification of actin by 4-hydroxy-trans-2-nonenal (HNE): LC-ESI-MS/MS evidence for Cys374 Michael adduction.
We demonstrate for the first time, by a combined mass spectrometric and computational approach, that G- and F-actin can be covalently modified by the lipid-derived aldehyde, 4-hydroxy-trans-2-nonenal, providing information on the molecular mass of modified protein and the mechanism and site of adduction.ESI-MS analysis of actin treated with different molar ratios of HNE (1 : 1 to 1 : 20) showed the formation of a protein derivative in which there was an increase of 156 Da (42028 Da) over native actin (41872 Da), consistent with the adduction of one HNE residue through Michael addition. To identify the site of HNE adduction, G- and F-actin were stabilized by NaBH(4) reduction and digested with trypsin. LC-ESI-MS/MS analysis in data-dependent scan mode of the resulting peptides unequivocally indicated that Cys374 is the site of HNE adduction. Computational studies showed that the reactivity of Cys374 residue is due to a significant accessible surface and substantial thiol acidity due to the particular microenvironment surrounding Cys374.
Aldini
Giancarlo
G
Istituto Chimico Farmaceutico Tossicologico, University of Milan, Viale Abruzzi 42, I-20131 Milan, Italy. giancarlo.aldini@unimi.it
Dalle-Donne
Isabella
I
Vistoli
Giulio
G
Maffei Facino
Roberto
R
Carini
Marina
M
D000199:Actins / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D002853:Chromatography, Liquid; D003545:Cysteine / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
D000199:Actins; D000447:Aldehydes; D010446:Peptide Fragments; C027576:4-hydroxy-2-nonenal; D003545:Cysteine