Purification, crystallization and preliminary X-ray analysis of the plectin actin-binding domain

Plectin is an abundantly expressed cytoskeletal crosslinking protein of enormous size (>500 kDa) and multiple functions. It represents one of the many members of a large family of actin-binding proteins. The actin-binding domain of mouse plectin was expressed in Escherichia coli and purified to homogeneity. Crystals of the actin-binding domain of plectin were prepared by the hanging-drop method. They belong to space group P2(1), with unit-cell parameters a = 55.92, b = 108.92, c = 63.75 Angstrom, beta = 115.25degrees. Data from a single crystal were collected to 2.0 Angstrom resolution at room temperature using synchrotron radiation at EMBL, Hamburg. The asymmetric unit contains two molecules of the protein, which corresponds to V-M = 3.06 Angstrom(3) Da(-1) and a solvent content of 60%. The structure was solved by the molecular-replacement method. In addition, the preparation of selenomethionine-derivative crystals is described.