2-DIMENSIONAL CRYSTALLIZATION OF THE CHAPERONIN TF55 FROM THE HYPERTHERMOPHILIC ARCHAEON SULFOLOBUS-SOLFATARICUS

Oligomers of the chaperonin TF55 from Sulfolobus solfataricus have bee n successfully crystallized in two dimensions via their interaction wi th a phospholipid monolayer at the air/liquid interface. Oligomer orie ntation was dependent upon the lipid headgroup used. A neutral lipid m onolayer gave rise to small paracrystalline areas of TF55 side views, whereas a negatively charged lipid monolayer resulted in large coheren t crystalline areas of the chaperonin in an end-on orientation. These 2D crystals had p312 symmetry (a = b = 162 Angstrom, gamma = 60 degree s). Two-dimensional projection structures of the end-on arrays were pr oduced by electron microscopy and image processing techniques. Under t he conditions used to grow the crystals, the protein formed complexes of two stacked nine-subunit rings with threefold symmetry. (C) 1998 Ac ademic Press.