Site-specific transamidation and deamidation of the small heat-shock protein Hsp20 by tissue transglutaminase.
Crosslinking of small heat-shock proteins (sHsps) by tissue transglutaminase (tTG) is enhanced by stress and under pathological conditions. We here used hexapeptide probes to determine the amine donor (K) and acceptor (Q) sites for tTG in Hsp20. Mass spectrometric peptide mass fingerprinting and peptide fragmentation established that Q31 and the C-terminal K162 are involved in inter- and intramolecular crosslinking (transamidation). Q31 is a conserved glutamine in sHsps where the neighboring residue determines its reactivity. Moreover, we detected highly efficient simultaneous deamidation of Q66, which suggests that tTG-catalyzed transamidation and deamidation is specific for different glutamine residues.
Boros
Sandor
S
Department of Biochemistry 271, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Nijmegen, The Netherlands.
Ahrman
Emma
E
Wunderink
Lisa
L
Kamps
Bram
B
de Jong
Wilfried W
WW
Boelens
Wilbert C
WC
Emanuelsson
Cecilia Sundby
CS
D000577:Amides / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli; D019204:GTP-Binding Proteins; D050886:HSP20 Heat-Shock Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D011503:Transglutaminases / Q000378:metabolism*
D000577:Amides; D050886:HSP20 Heat-Shock Proteins; D011994:Recombinant Proteins; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins