CryoEM structures of human CMG-ATPγS-DNA and CMG-AND-1 complexes.
Nucleic Acids Res
; 48(12): 6980-6995, 2020 07 09.
Article
en En
| MEDLINE
| ID: mdl-32453425
ABSTRACT
DNA unwinding in eukaryotic replication is performed by the Cdc45-MCM-GINS (CMG) helicase. Although the CMG architecture has been elucidated, its mechanism of DNA unwinding and replisome interactions remain poorly understood. Here we report the cryoEM structure at 3.3 Å of human CMG bound to fork DNA and the ATP-analogue ATPγS. Eleven nucleotides of single-stranded (ss) DNA are bound within the C-tier of MCM2-7 AAA+ ATPase domains. All MCM subunits contact DNA, from MCM2 at the 5'-end to MCM5 at the 3'-end of the DNA spiral, but only MCM6, 4, 7 and 3 make a full set of interactions. DNA binding correlates with nucleotide occupancy five MCM subunits are bound to either ATPγS or ADP, whereas the apo MCM2-5 interface remains open. We further report the cryoEM structure of human CMG bound to the replisome hub AND-1 (CMGA). The AND-1 trimer uses one ß-propeller domain of its trimerisation region to dock onto the side of the helicase assembly formed by Cdc45 and GINS. In the resulting CMGA architecture, the AND-1 trimer is closely positioned to the fork DNA while its CIP (Ctf4-interacting peptide)-binding helical domains remain available to recruit partner proteins.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
ADN
/
Proteínas de Ciclo Celular
/
Complejos Multiproteicos
/
Proteínas de Mantenimiento de Minicromosoma
Límite:
Humans
Idioma:
En
Año:
2020
Tipo del documento:
Article