CDK promotes interactions of Sld3 and Drc1 with Cut5 for initiation of DNA replication in fission yeast

Abstract

Study of the essential roles of CDK in initiation of DNA replication in fission yeast indicates that CDK phosphorylates Sld3 and Drc1/Sld2 and promotes their interactions with Cut5, which are required for origin loading of Cut5. Thus CDK regulates assembly of replication factors onto origins by promoting ternary Sld3–Cut5–Drc1 complex formation.

Mcm10 interacts with Rad4/Cut5TopBP1 and its association with origins of DNA replication is dependent on Rad4/Cut5TopBP1

“…Interestingly the Sld3 result contrasts with earlier data indicating that Sld3 can associate with the pre-RC in the absence of detectable Rad4 TopBP1 origin association when CDK levels are reduced (24). Additionally a mutated form of Sld3 impaired in its interaction with Rad4 TopBP1 shows increased levels of origin association relative to wild type Sld3 and that association occurs in the absence of Rad4 TopBP1 association (48).…”

“…One possible explanation for these contrasting observations might be that in the wild type situation the stability of preRC association of Sld3 and Rad4 TopBP1 is mutually dependent and that the experimental interventions employed in the different studies perturb this relationship. The phosphorylation-dependent Rad4 TopBP1 interaction with Sld2 and Sld3 is conserved between budding and fission yeast (48). Indeed the conservation of the TopBP1-Sld3 interaction has recently been extended to human cells (49).…”

Helicase Activation and Establishment of Replication Forks at Chromosomal Origins of Replication

“…The CDK-catalyzed phosphorylation of Drc1 and Sld3 facilitates the interaction between Cut5 and Drc1 and Sld3, as observed in budding yeast (Saka et al 1994;Nakajima and Masukata 2002;Noguchi et al 2002;Fukuura et al 2011). However, phosphorylation of Sld3 is not essential, although it is important, for the association of Cut5 with origins; the disruption of phosphorylation sites reduces the interaction between Cut5 and Sld3 and renders cells sensitive to low temperature (Nakajima and Masukata 2002;Fukuura et al 2011). Interestingly, the interaction between Cut5 and Drc1 further enhances the interaction with Sld3 (Fukuura et al 2011).…”

“…However, phosphorylation of Sld3 is not essential, although it is important, for the association of Cut5 with origins; the disruption of phosphorylation sites reduces the interaction between Cut5 and Sld3 and renders cells sensitive to low temperature (Nakajima and Masukata 2002;Fukuura et al 2011). Interestingly, the interaction between Cut5 and Drc1 further enhances the interaction with Sld3 (Fukuura et al 2011). Sld3 associates with replication origins before initiation in a DDK-dependent manner (Yabuuchi et al 2006), and its association with origins is a prerequisite for the subsequent recruitment of Cut5, GINS, Drc1, and Cdc45 (Yabuuchi et al 2006).…”

Cyclin-dependent kinase regulates the length of S phase through TICRR/TRESLIN phosphorylation

“…First, Sld3 binds to Cdc45 and is recruited to replication origins in a DDK-dependent manner (Kamimura et al 2001;Heller et al 2011;Tanaka et al 2011). Next, CDK phosphorylates Sld3, causing it to associate with Dpb11 (Tanaka et al 2007;Zegerman and Diffley 2007;Fukuura et al 2011). In S. cerevisiae, if preinitiation complexes are exposed to CDK prior to DDK, DNA replication does not occur (Heller et al 2011).…”