Proliferating cell nuclear antigen uses two distinct modes to move along DNA.
Proliferating cell nuclear antigen (PCNA) plays an important role in eukaryotic genomic maintenance by topologically binding DNA and recruiting replication and repair proteins. The ring-shaped protein forms a closed circle around double-stranded DNA and is able to move along the DNA in a random walk. The molecular nature of this diffusion process is poorly understood. We use single-molecule imaging to visualize the movement of individual, fluorescently labeled PCNA molecules along stretched DNA. Measurements of diffusional properties as a function of viscosity and protein size suggest that PCNA moves along DNA using two different sliding modes. Most of the time, the clamp moves while rotationally tracking the helical pitch of the DNA duplex. In a less frequently used second mode of diffusion, the movement of the protein is uncoupled from the helical pitch, and the clamp diffuses at much higher rates.
Graduate Program in Biophysics, Harvard University, Cambridge, Massachusetts 02138, USA.
Anna B
AB
Kochaniak
Satoshi
S
Habuchi
Joseph J
JJ
Loparo
Debbie J
DJ
Chang
Karlene A
KA
Cimprich
Johannes C
JC
Walter
Antoine M
AM
van Oijen
D000818:Animals; D004247:DNA / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D045663:Quantum Dots; D014982:Xenopus laevis / Q000254:growth & development / Q000378:metabolism*
D018809:Proliferating Cell Nuclear Antigen; D004247:DNA; D004259:DNA-Directed DNA Polymerase