Isopeptidase activity of human transglutaminase 2: Disconnection from transamidation and characterization by kinetic parameters

Róbert Király, Kiruphagaran Thangaraju, Zsófia Nagy, Russell Collighan, Zoltán Nemes, Martin Griffin, László Fésüs

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Transglutaminase 2 (TG2) is a multifunctional protein with diverse catalytic activities and biological roles. Its best studied function is the Ca2+-dependent transamidase activity leading to formation of γ-glutamyl-ε-lysine isopeptide crosslinks between proteins and γ-glutamyl-amine derivatives. TG2 has a poorly studied isopeptidase activity cleaving these bonds. We have developed and characterised TG2 mutants which are significantly deficient in transamidase activity while have normal or increased isopeptidase activity (W332F) and vice versa (W278F). The W332F mutation led to significant changes of both the K m and the V max kinetic parameters of the isopeptidase reaction of TG2 while its calcium and GTP sensitivity was similar to the wild-type enzyme. The W278F mutation resulted in six times elevated amine incorporating transamidase activity demonstrating the regulatory significance of W278 and W332 in TG2 and that mutations can change opposed activities located at the same active site. The further application of our results in cellular systems may help to understand TG2-driven physiological and pathological processes better and lead to novel therapeutic approaches where an increased amount of crosslinked proteins correlates with the manifestation of degenerative disorders.

Original languageEnglish
Pages (from-to)31-40
Number of pages10
JournalAmino Acids
Volume48
Issue number1
DOIs
Publication statusPublished - Jan 1 2016

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Keywords

  • Human transglutaminase 2
  • Isopeptidase activity
  • Moonlighting enzyme
  • Regulation of activities
  • Transamidation
  • γ-Glutamyl-hydrolase

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Organic Chemistry

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