Interaction between human Ctf4 and the Cdc45/Mcm2-7/GINS (CMG) replicative helicase

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 49; pp. 19760 - 19765
• Main Authors: Kang, Young-Hoon, Farina, Andrea, Bermudez, Vladimir P., Tappin, Inger, Du, Fang, Galal, Wiebke Chemnitz, Hurwitz, Jerard
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.12.2013; NATIONAL ACADEMY OF SCIENCES; National Acad Sciences
• Subjects: Animals; Biological Sciences; Blotting, Western; Cell Cycle Proteins - metabolism; Chromatin; Chromosomes; Densitometry; Dimerization; Dimers; DNA; DNA Helicases - metabolism; DNA Primers - genetics; DNA replication; DNA Replication - physiology; DNA-Binding Proteins - metabolism; Enzymes; Gels; Gin; HeLa cells; Humans; Immunoprecipitation; Minichromosome Maintenance Proteins - metabolism; Multiprotein Complexes - metabolism; Oligonucleotides - genetics; Proteins; Saccharomycetales; Sf9 Cells; Spodoptera; Spodoptera frugiperda; Yeasts; dimerization; replication initiation; replisome core structure
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1320202110

Chromosome transmission fidelity 4 (Ctf4) is a conserved protein required for DNA replication. In this report, interactions between human Ctf4 (hCtf4) and the replicative helicase containing the cell division cycle 45 (Cdc45)/minichromosome maintenance 2-7 (Mcm2-7)/Go, Ichi, Nii, and San (GINS) (CMG) proteins [human CMG (hCMG) complex] were examined. The hCtf4–CMG complex was isolated following in vitro interaction of purified proteins (hCtf4 plus the hCMG complex), coinfection of Spodoptera frugiperda (Sf9) insect cells with viruses expressing the hCMG complex and hCtf4, and from HeLa cell chromatin after benzonase and immunoprecipitation steps. The stability of the hCtf4–CMG complex depends upon interactions between hCtf4 and multiple components of the hCMG complex. The hCtf4–CMG complex, like the hCMG complex, contains DNA helicase activity that is more salt-resistant than the helicase activity of the hCMG complex. We demonstrate that the hCtf4–CMG complex contains a homodimeric hCtf4 and a monomeric hCMG complex and suggest that the homodimeric hCtf4 acts as a platform linking polymerase α to the hCMG complex. The role of the hCMG complex as the core of the replisome is also discussed.