Hexameric ring structure of the full-length archaeal MCM protein complex |
| |
Authors: | Pape Tillmann Meka Hedije Chen Shaoxia Vicentini Giorgia van Heel Marin Onesti Silvia |
| |
Affiliation: | Department of Biological Sciences, Imperial College, London SW7 2AZ, UK. |
| |
Abstract: | In eukaryotes, a family of six homologous minichromosome maintenance (MCM) proteins has a key function in ensuring that DNA replication occurs only once before cell division. Whereas all eukaryotes have six paralogues, in some Archaea a single protein forms a homomeric assembly. The complex is likely to function as a helicase during DNA replication. We have used electron microscopy to obtain a three-dimensional reconstruction of the full-length MCM from Methanobacterium thermoautotrophicum. Six monomers are arranged around a sixfold axis, generating a ring-shaped molecule with a large central cavity and lateral holes. The channel running through the molecule can easily accommodate double-stranded DNA. The crystal structure of the amino-terminal fragment of MCM and a model for the AAA+ hexamer have been docked into the map, whereas additional electron density suggests that the carboxy-terminal domain is located at the interface between the two domains. The structure suggests that the MCM complex is likely to act in a different manner to traditional hexameric helicases and is likely to bear more similarity to the SV40 large T antigen or to double-stranded DNA translocases. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|