Cryo-electron microscopy reveals a novel DNA-binding site on the MCM helicase.
The eukaryotic MCM2-7 complex is recruited at origins of replication during the G1 phase and acts as the main helicase at the replication fork during the S phase of the cell cycle. To characterize the interplay between the MCM helicase and DNA prior to the melting of the double helix, we determined the structure of an archaeal MCM orthologue bound to a 5.6-kb double-stranded DNA segment, using cryo-electron microscopy. DNA wraps around the N-terminal face of a single hexameric ring. This interaction requires a conformational change within the outer belt of the MCM N-terminal domain, exposing a previously unrecognized helix-turn-helix DNA-binding motif. Our findings provide novel insights into the role of the MCM complex during the initiation step of DNA replication.
Costa
Alessandro
A
Department of Life Sciences, Imperial College London, London, UK.
van Duinen
Gijs
G
Medagli
Barbara
B
Chong
James
J
Sakakibara
Nozomi
N
Kelman
Zvi
Z
Nair
Satish K
SK
Patwardhan
Ardan
A
Onesti
Silvia
S
D001665:Binding Sites; D020285:Cryoelectron Microscopy; D004247:DNA / Q000648:ultrastructure*; D004265:DNA Helicases / Q000737:chemistry* / Q000648:ultrastructure*; D017013:Methanobacteriaceae / Q000201:enzymology*; D008958:Models, Molecular; D050505:Mutant Proteins / Q000648:ultrastructure; D011485:Protein Binding; D017434:Protein Structure, Tertiary
D050505:Mutant Proteins; D004247:DNA; D004265:DNA Helicases