EMD-3644
Full-length CMG helicase complex
EMD-3644
Single-particle23.7 Å
Deposition: 20/03/2017Map released: 12/04/2017
Last modified: 26/04/2017
Sample Organism:
Saccharomyces cerevisiae
Sample: CMG helicase
Deposition Authors: Zhou JC, Janska A, Goswami P, Renault L, Abid Ali F, Kotecha A, Diffley JFX, Costa A
Sample: CMG helicase
Deposition Authors: Zhou JC, Janska A, Goswami P, Renault L, Abid Ali F, Kotecha A, Diffley JFX, Costa A
CMG-Pol epsilon dynamics suggests a mechanism for the establishment of leading-strand synthesis in the eukaryotic replisome.
Zhou JC 
,
Janska A,
Goswami P,
Renault L ,
Abid Ali F ,
Kotecha A ,
Diffley JFX ,
Costa A
(2017) PNAS , 114 , 4141 - 4146
,
Janska A,
Goswami P,
Renault L ,
Abid Ali F ,
Kotecha A ,
Diffley JFX ,
Costa A
(2017) PNAS , 114 , 4141 - 4146
Abstract:
The replisome unwinds and synthesizes DNA for genome duplication. In eukaryotes, the Cdc45-MCM-GINS (CMG) helicase and the leading-strand polymerase, Pol epsilon, form a stable assembly. The mechanism for coupling DNA unwinding with synthesis is starting to be elucidated, however the architecture and dynamics of the replication fork remain only partially understood, preventing a molecular understanding of chromosome replication. To address this issue, we conducted a systematic single-particle EM study on multiple permutations of the reconstituted CMG-Pol epsilon assembly. Pol epsilon contains two flexibly tethered lobes. The noncatalytic lobe is anchored to the motor of the helicase, whereas the polymerization domain extends toward the side of the helicase. We observe two alternate configurations of the DNA synthesis domain in the CMG-bound Pol epsilon. We propose that this conformational switch might control DNA template engagement and release, modulating replisome progression.
The replisome unwinds and synthesizes DNA for genome duplication. In eukaryotes, the Cdc45-MCM-GINS (CMG) helicase and the leading-strand polymerase, Pol epsilon, form a stable assembly. The mechanism for coupling DNA unwinding with synthesis is starting to be elucidated, however the architecture and dynamics of the replication fork remain only partially understood, preventing a molecular understanding of chromosome replication. To address this issue, we conducted a systematic single-particle EM study on multiple permutations of the reconstituted CMG-Pol epsilon assembly. Pol epsilon contains two flexibly tethered lobes. The noncatalytic lobe is anchored to the motor of the helicase, whereas the polymerization domain extends toward the side of the helicase. We observe two alternate configurations of the DNA synthesis domain in the CMG-bound Pol epsilon. We propose that this conformational switch might control DNA template engagement and release, modulating replisome progression.