The amine-donor substrate specificity of tissue-type transglutaminase. Influence of amino acid residues flanking the amine-donor lysine residue.
The amine-donor substrate specificity of tissue-type transglutaminase has been studied in a series of recombinant alpha A-crystallin mutants. These mutant proteins have been provided with a potential substrate lysine residue, flanked by different amino acid residues, in the C-terminal extended arm of alpha A-crystallin. A biotinylated amine-acceptor hexapeptide was used as a probe for labelling the amine-donor sites. Wild-type bovine alpha A-crystallin does not function as an amine-donor substrate for tissue-type transglutaminase. Yet, upon introduction of a lysine residue at the C-terminal or penultimate position, all mutant alpha A-crystallins act as amine-donor substrates, although to different extents. This shows that accessibility is the primary requirement for a lysine residue to function as an amine-donor substrate for transglutaminase and that the enzyme has a broad tolerance towards the neighbouring residues. However, the nature of the flanking amino acid residues does clearly affect the reactivity of the substrate lysine residue. Notably, we found that a proline or glycine residue in front of the substrate lysine has a strong adverse effect on the substrate reactivity as compared to a preceding leucine, serine, alanine or arginine residue.
Groenen
P J
PJ
Department of Biochemistry, University of Nijmegen, The Netherlands.
Smulders
R H
RH
Peters
R F
RF
Grootjans
J J
JJ
van den Ijssel
P R
PR
Bloemendal
H
H
de Jong
W W
WW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003459:Crystallins / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D011503:Transglutaminases / Q000378:metabolism*
D003459:Crystallins; D011503:Transglutaminases; D008239:Lysine