Structure of the Heterotrimeric PCNA from Sulfolobus Solfataricus.
Williams, G.J., Johnson, K., Rudolf, J., Mcmahon, S.A., Carter, L., Oke, M., Liu, H., Taylor, G.L., White, M.F., Naismith, J.H.(2006) Acta Crystallogr Sect F Struct Biol Cryst Commun 62: 944
- PubMed: 17012780 
- DOI: https://doi.org/10.1107/S1744309106034075
- Primary Citation of Related Structures:  
2IX2 - PubMed Abstract: 
PCNA is a ring-shaped protein that encircles DNA, providing a platform for the association of a wide variety of DNA-processing enzymes that utilize the PCNA sliding clamp to maintain proximity to their DNA substrates. PCNA is a homotrimer in eukaryotes, but a heterotrimer in crenarchaea such as Sulfolobus solfataricus. The three proteins are SsoPCNA1 (249 residues), SsoPCNA2 (245 residues) and SsoPCNA3 (259 residues). The heterotrimeric protein crystallizes in space group P2(1), with unit-cell parameters a = 44.8, b = 78.8, c = 125.6 A, beta = 100.5 degrees. The crystal structure of this heterotrimeric PCNA molecule has been solved using molecular replacement. The resulting structure to 2.3 A sheds light on the differential stabilities of the interactions observed between the three subunits and the specificity of individual subunits for partner proteins.
Organizational Affiliation: 
Centre for Biomolecular Science and The Scottish Structural Proteomics Facility, The University of St Andrews, Fife KY16 9RH, Scotland.