Crystallization, X-ray diffraction and preliminary structure analysis of Mycobacterium tuberculosis chaperonin 10

Mycobacterium tuberculosis chaperonin 10 (Mtcpn10) has been crystallized by the sitting-drop vapour-diffusion method. The crystals belong to the monoc linic space group P2(1), with unit-cell parameters a = 76.5. b = 87.9, c = 124.4 Angstrom, beta = 106.8 degrees. X-ray diffraction data were collected to 2.8 Angstrom. The self-rotation function and the molecular-replacement solution show that the asymmetric unit contains a dimer of heptamers relate d by twofold non-crystallographic symmetry. The two heptamers interact thro ugh interleaving flexible loops in a similar fashion to M. leprae and Gp31 cpn10. In addition to its role in protein folding, Mtcpn10 has unique effec ts on the growth of host cells and is a major immunogen in tuberculosis inf ections The structure determination will permit the analysis of the amino a cids identified as important for the protein-folding and cell-signalling ac tivity of Mtcpn10.