Interactions between the archaeal Cdc6 and MCM proteins modulate their biochemical properties.
The origin recognition complex, Cdc6 and the minichromosome maintenance (MCM) complex play essential roles in the initiation of eukaryotic DNA replication. Homologs of these proteins may play similar roles in archaeal replication initiation. While the interactions among the eukaryotic initiation proteins are well documented, the protein-protein interactions between the archaeal proteins have not yet been determined. Here, an extensive structural and functional analysis of the interactions between the Methanothermobacter thermautotrophicus MCM and the two Cdc6 proteins (Cdc6-1 and -2) identified in the organism is described. The main contact between Cdc6 and MCM occurs via the N-terminal portion of the MCM protein. It was found that Cdc6-MCM interaction, but not Cdc6-DNA binding, plays the predominant role in regulating MCM helicase activity. In addition, the data showed that the interactions with MCM modulate the autophosphorylation of Cdc6-1 and -2. The results also suggest that MCM and DNA may compete for Cdc6-1 protein binding. The implications of these observations for the initiation of archaeal DNA replication are discussed.
Kasiviswanathan
Rajesh
R
University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology, 9600 Gudelsky Drive, Rockville, MD 20850, USA.
Shin
Jae-Ho
JH
Kelman
Zvi
Z
D001105:Archaea / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D017013:Methanobacteriaceae / Q000201:enzymology; D051738:Origin Recognition Complex; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D020798:Two-Hybrid System Techniques
D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D051738:Origin Recognition Complex; D004265:DNA Helicases