Crystal structure of a naturally occurring parallel right-handed coiled coil tetramer

The crystal structure of a polypeptide chain fragment from the surface laye r protein tetrabrachion from Staphylothermus marinus has been determined at 1.8 Angstrom resolution. As proposed on the basis of the presence of 11-re sidue repeats, the polypeptide chain fragment forms a parallel right-handed coiled coil structure. Complementary hydrophobic interactions and complex networks of surface salt bridges result En an extremely thermostable tetram eric structure with remarkable properties. In marked contrast to left-hande d coiled coil tetramers, the right-handed coiled coil reveals large hydroph obic cavities that are filled with water molecules. As a consequence, the p acking of the hydrophobic core differs markedly from that of a right-handed parallel coiled coil tetramer that was designed on the basis of left-hande d coiled coil structures.