Dissecting the interaction between transglutaminase 2 and fibronectin
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In the extracellular environment, the enzyme transglutaminase 2 (TG2) is involved in cell–matrix interactions through association with the extracellular matrix protein, fibronectin (FN). The 45 kDa gelatin-binding domain of FN (45FN) is responsible for the binding to TG2. Previous studies have demonstrated that the FN-binding site of TG2 is located in the N-terminal domain of the enzyme although with conflicting results regarding the specific residues involved. Here we have mapped the FN interaction site of human TG2 by use of hydrogen/deuterium exchange coupled with mass spectrometry, and we confirm that the FN-binding site is located in the N-terminal domain of TG2. Furthermore, by combination of site-directed mutagenesis and surface plasmon resonance analysis we have identified the TG2 residues K30, R116 and H134 as crucial to maintain the high affinity interaction with FN. Mutation of all three residues simultaneously reduced binding to 45FN by more than 2000-fold. We also identified residues in the catalytic core domain of TG2 that contributed to FN binding, hence extending the binding interface between TG2 and FN. This study provides new insights into the high affinity interaction between TG2 and FN.
KeywordsTransglutaminase 2 Fibronectin Hydrogen/deuterium exchange Site-directed mutagenesis Surface plasmon resonance
45 kDa proteolytic fibronectin fragment (gelatin-binding domain)
Hydrogen/deuterium exchange coupled with mass spectrometry
Surface plasmon resonance
TG2 mutant R116A/H134A
TG2 mutant K30E/R116A/H134A
This work was supported by the European Commission grants MRTN-CT-2006-036032 and ERC-2010-Ad-268541 and Grants from the Research Council of Norway and the South-Eastern Norway Regional Health Authority. The authors thank Chaitan Khosla (Stanford University, CA; USA) for providing the TG3 plasmid.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human and animal rights statement
This article does not contain any studies with human participants or animals performed by any of the authors.
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