3RTK

Crystal structure of Cpn60.2 from Mycobacterium tuberculosis at 2.8A

Summary for 3RTK

• Entry DOI: 10.2210/pdb3rtk/pdb
• Descriptor: 60 kDa chaperonin 2, MAGNESIUM ION (3 entities in total)
• Functional Keywords: heat shock protein, chaperonin, chaperone
• Biological source: Mycobacterium tuberculosis
• Cellular location: Cytoplasm (By similarity): P0A520
• Total number of polymer chains: 2
• Total formula weight: 115269.01

Authors

Shahar, A.,Melamed-Frank, M.,Kashi, Y.,Adir, N. (deposition date: 2011-05-03, release date: 2011-08-10, Last modification date: 2023-09-13)

Primary citation

Shahar, A.,Melamed-Frank, M.,Kashi, Y.,Shimon, L.,Adir, N.
The dimeric structure of the Cpn60.2 chaperonin of Mycobacterium tuberculosis at 2.8 A reveals possible modes of function.
J.Mol.Biol., 412:192-203, 2011

PubMed Abstract: Mycobacterium tuberculosis expresses two proteins (Cpn60.1 and Cpn60.2) that belong to the chaperonin (Cpn) family of heat shock proteins. Studies have shown that the two proteins have different functional roles in the bacterial life cycle and that Cpn60.2 is essential for cell viability and may be involved in M. tuberculosis pathogenicity. Cpn60.2 does not form a tetradecameric double ring, which is typical of other Cpns. We have determined the crystal structure of recombinant Cpn60.2 to 2.8 Å resolution by molecular replacement; the asymmetric unit (AU) contains a dimer, which is consistent with size-exclusion high-performance liquid chromatography and dynamic light-scattering measurements of the soluble recombinant protein. However, we suggest that the actual Cpn60.2 dimer may be different from that identified within the AU on the basis of surface contact stability, solvation free-energy gain, and functional aspects. Unlike the dimer found in the AU, which is formed through apical domain interactions, the dimeric form we propose here provides a free apical domain that is required for normal chaperone activity and may be involved in M. tuberculosis association with macrophages and arthrosclerosis plaque formation. Here we describe in detail the structural aspects that lead to Cpn60.2 dimer formation and prevent the formation of heptameric rings and tetradecameric double rings.

PubMed: 21802426
DOI: 10.1016/j.jmb.2011.07.026

Experimental method

X-RAY DIFFRACTION (2.8 Å)