title: A novel heterotetrameric structure of the crenarchaeal PCNA2-PCNA3 complex.
abstract: Proliferating cell nuclear antigen (PCNA) is a key protein that orchestrates the arrangement of DNA-processing proteins on DNA during DNA metabolism. In crenarchaea, PCNA forms a heterotrimer (PCNA123) consisting of PCNA1, PCNA2, and PCNA3, while in most eukaryotes and many archaea PCNAs form a homotrimer. Interestingly, unique oligomeric PCNAs from Sulfolobus tokodaii were reported in which PCNA2 and PCNA3 form a heterotrimer without PCNA1. In this paper, we describe the crystal structure of the stoPCNA2-stoPCNA3 complex. While most DNA sliding clamps form ring-shaped structures, our crystal structure showed an elliptic ring-like heterotetrameric complex, differing from a previous reports. Furthermore, we investigated the composition and the dimension of the stoPCNA2-stoPCNA3 complex in the solution using gel-filtration column chromatography and small-angle X-ray scattering analyses, respectively. These results indicate that stoPCNA2 and stoPCNA3 form the heterotetramer in solution. Based on our heterotetrameric structure, we propose a possible biological role for the heterotetrameric complex as a Holliday junction clamp.
authors.affiliation: Sojo University, Ikeda, Kumamoto, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Kawai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Shigesada
authors.initials: S
authors.lastname: Higuchi
authors.forename: Masaru
authors.initials: M
authors.lastname: Tsunoda
authors.forename: Mamoru
authors.initials: M
authors.lastname: Sato
authors.forename: Kazuo T
authors.initials: KT
authors.lastname: Nakamura
authors.forename: Shuichi
authors.initials: S
authors.lastname: Miyamoto
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D045566:DNA, Cruciform; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry*; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry*; D020033:Protein Isoforms / Q000737:chemistry*; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry*; D053838:Scattering, Small Angle; D016944:Sulfolobus / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins; D045566:DNA, Cruciform; D046912:Multiprotein Complexes; D018809:Proliferating Cell Nuclear Antigen; D020033:Protein Isoforms; D021122:Protein Subunits