The structure of the FERM domain of merlin, the neurofibromatosis type 2 gene product

Neurofibromatosis type 2 is an autosomal dominant disorder characterized by central nervous system tumors. The cause of the disease has been traced to mutations in the gene coding for a protein that is alternately called merlin or schwannomin and is a member of the ERM family (ezrin, radixin and moesin). The ERM proteins link the cytoskeleton to the cell membrane either directly through integral membrane proteins or indirectly through membrane-associated proteins. In this paper, the expression, purification, crystallization and crystal structure of the N-terminal domain of merlin are described. The crystals exhibit the symmetry of space group P2₁2₁2₁, with two molecules in the asymmetric unit. The recorded diffraction pattern extends to 1.8 Å resolution. The structure was solved by the molecular-replacement method and the model was refined to a conventional R value of 19.3% (R_free = 22.7%). The N-terminal domain of merlin closely resembles those described for the corresponding domains in moesin and radixin and exhibits a cloverleaf architecture with three distinct subdomains. The structure allows a better rationalization of the impact of selected disease-causing mutations on the integrity of the protein.