Unveiling the Molecular Basis of the Noonan Syndrome-Causing Mutation T42A of SHP2.
Noonan syndrome (NS) is a genetic disorder caused by the hyperactivation of the RAS-MAPK molecular pathway. About 50% of NS cases are caused by mutations affecting the SHP2 protein, a multi-domain phosphatase with a fundamental role in the regulation of the RAS-MAPK pathway. Most NS-causing mutations influence the stability of the inactive form of SHP2. However, one NS-causing mutation, namely T42A, occurs in the binding pocket of the N-SH2 domain of the protein. Here, we present a quantitative characterization of the effect of the T42A mutation on the binding of the N-terminal SH2 domain of SHP2 with a peptide mimicking Gab2, a fundamental interaction that triggers the activation of the phosphatase in the cellular environment. Our results show that whilst the T42A mutation does not affect the association rate constant with the ligand, it causes a dramatic increase of the affinity for Gab2. This effect is due to a remarkable decrease of the microscopic dissociation rate constant of over two orders of magnitudes. In an effort to investigate the molecular basis of the T42A mutation in causing Noonan syndrome, we also compare the experimental results with a more conservative variant, T42S. Our findings are discussed in the context of the structural data available on SHP2.
['Toto|Angelo|A|', 'Malagrinò|Francesca|F|', 'Visconti|Lorenzo|L|', 'Troilo|Francesca|F|', 'Gianni|Stefano|S|']
D048868:Adaptor Proteins, Signal Transducing D020022:Genetic Predisposition to Disease D006801:Humans D007700:Kinetics D008958:Models, Molecular D016296:Mutagenesis D009154:Mutation D009634:Noonan Syndrome D011485:Protein Binding D011487:Protein Conformation D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 D018909:src Homology Domains
kinetics mutagenesis protein binding