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 P2(1)2(1)2(1), with two molecules in the asymmetric unit. The recorded diffraction pattern extends to 1.8A 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.