title: Three proliferating cell nuclear antigen homologues from Metallosphaera sedula form a head-to-tail heterotrimer.
abstract: Proliferating cell nuclear antigen (PCNA) is a sliding clamp that plays a key role in DNA metabolism. Genome sequence analysis has revealed that some crenarchaea possess three PCNA genes in their genome, but it has been reported that three PCNAs do not always form a unique heterotrimer composed of one of each molecule. The thermoacidophilic archaeon, Metallosphaera sedula, has three PCNA homologue genes. Here, we demonstrated that the three PCNA homologues, MsePCNA1, MsePCNA2 and MsePCNA3, exclusively form a heterotrimer in a stepwise fashion; MsePCNA1 and MsePCNA2 form a heterodimer, and then MsePCNA3 binds to the heterodimer. We determined that the dissociation constants between MsePCNA1 and MsePCNA2, and between MsePCNA3 and the MsePCNA1:MsePCNA2 heterodimer are 0.29 and 43 nM, respectively. Moreover, the MsePCNA1, MsePCNA2 and MsePCNA3 heterotrimer stimulated M. sedula DNA ligase 1 activity, suggesting that the heterotrimer works as a DNA sliding clamp in the organism. The stable and stepwise heterotrimerization of M. sedula PCNA homologues would be useful to generate functional protein-based materials such as artificial multi-enzyme complexes, functional hydrogels and protein fibres, which have recently been achieved by protein self-assembly.
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Fumiya
authors.initials: F
authors.lastname: Iwata
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Hirakawa
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nagamune
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002850:Chromatography, Gel; D007700:Kinetics; D008958:Models, Molecular; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000072417:Protein Domains; D055503:Protein Multimerization; D017386:Sequence Homology, Amino Acid; D016943:Sulfolobaceae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020349:Surface Plasmon Resonance
chemical_list: D019843:Archaeal Proteins; D018809:Proliferating Cell Nuclear Antigen