Transglutaminase 2 mediates polymer formation of I-kappaBalpha through C-terminal glutamine cluster.

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Park SS, Kim JM, Kim DS, Kim IH, Kim SY

Transglutaminase 2 mediates polymer formation of I-kappaBalpha through C-terminal glutamine cluster.

J Biol Chem. 2006 Nov 17;281(46):34965-72. Epub 2006 Sep 20.

PubMed ID

16987813 [ View in PubMed

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Abstract

Recently we reported that transglutaminase 2 (TGase 2) activates nuclear factor-kappaB (NF-kappaB) independently of I-kappaB kinase (IKK) activation, by inducing cross-linking and protein polymer formation of inhibitor of nuclear factor-kappaBalpha (I-kappaBalpha). TGase 2 catalyzes covalent isopeptide bond formation between the peptide bound-glutamine and the lysine residues. Using matrix-assisted laser desorption ionization time-of-flight mass spectra analysis of I-kappaBalpha polymers cross-linked by TGase 2, as well as synthetic peptides in an in vitro competition assay, we identified a glutamine cluster at the C terminus of I-kappaBalpha (amino acids 266-268) that appeared to play a key role in the formation of I-kappaBalpha polymers. Although there appeared to be no requirement for specific lysine residues, we found a considerably higher preference for the use of lysine residues at positions 21, 22, and 177 in TGase 2-mediated cross-linking of I-kappaBalpha. We demonstrated that synthetic peptides encompassing the glutamine cluster at amino acid positions 266-268 reversed I-kappaBalpha polymerization in vitro. Furthermore, the depletion of free I-kappaBalpha in EcR/TG cells was completely rescued in vivo by transfection of mutant I-kappaBalphas in glutamine sites (Q266G, Q267G, and Q313G) as well as in a lysine site (K177G). These findings provide additional clues into the mechanism by which TGase 2 contributes to the inflammatory process via activation of NF-kappaB.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
L-Glutamine	Protein-glutamine gamma-glutamyltransferase 2	Protein	Humans	Unknown	Substrate	Details