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J. Mol. Micro. Biotechnol. 3: 73-82

Protein-Protein Interaction Between Bacillus stearothermophilus Tyrosyl-tRNA Synthetase Subdomains Revealed by a Bacterial Two-Hybrid System

Gouzel Karimova, Agnes Ullmann and Daniel Ladant

We have recently developed a bacterial two-hybrid system (BACTH), based on functional complementation between two fragments of the catalytic domain of Bordetella pertussis adenylate cyclase (AC), that allows an easy in vivo screening and selection of functional interactions between two proteins in Escherichia coli. In this work, we have further explored the potentialities of the BACTH system to study protein-protein interactions, using as a model, the interactions between various subdomains of the dimeric tyrosyl-tRNA synthetase (TyrRS) of Bacillus stearothermophilus. Using the BACTH system we confirmed the known interactions of the a/b domains and those between the a/b domain and the a domain that could be anticipated from the three-dimensional structure of TyrRS. Interestingly, the BACTH system revealed the unexpected interaction between the TyrRS a domains which is presumably mediated by a pseudo-leucine zipper motif. This study illustrates the interest of the bacterial two-hybrid system to delineate interacting domains of proteins and shows that it can reveal interactions that occur in vivo and that were not anticipated from the three-dimensional structure of the protein of interest.

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