title: PCNA appears in two populations of slow and fast diffusion with a constant ratio throughout S-phase in replicating mammalian cells.
abstract: DNA replication is a fundamental cellular process that precedes cell division. Proliferating cell nuclear antigen (PCNA) is a central scaffold protein that orchestrates DNA replication by recruiting many factors essential for the replication machinery. We studied the mobility of PCNA in live mammalian cells using single-particle tracking in combination with photoactivated-localization microscopy (sptPALM) and found two populations. The first population which is only present in cells with active DNA replication, showed slow diffusion and was found to be located in replication foci. The second population showed fast diffusion, and represents the nucleoplasmic pool of unbound PCNA not involved in DNA replication. The ratio of these two populations remained constant throughout different stages of S-phase. A fraction of molecules in both populations showed spatially constrained mobility. We determined an exploration radius of ~100 nm for 13% of the slow-diffusing PCNA molecules, and of ~600 nm for 46% of the fast-diffusing PCNA molecules.
authors.affiliation: Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Patrick J M
authors.initials: PJ
authors.lastname: Zessin
authors.affiliation: Advanced Light Microscopy, Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Anje
authors.initials: A
authors.lastname: Sporbert
authors.affiliation: Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Heilemann
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D004261:DNA Replication; D004058:Diffusion; D006801:Humans; D057054:Molecular Imaging; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D021381:Protein Transport; D016196:S Phase
chemical_list: D018809:Proliferating Cell Nuclear Antigen