title: Treslin, DUE-B, and GEMC1 cannot complement Sld3 mutants in fission yeast.
abstract: Initiation of DNA replication in eukaryotes is an evolutionarily conserved process that involves two distinct steps: the formation of prereplication complexes at replication origins in G1 and the assembly of preinitiation complexes (pre-ICs) in S phase, which leads to activation of the replication helicase. For the assembly of pre-ICs in yeast, formation of the Sld2-Dpb11-Sld3 complex is a critical event that requires phosphorylation of Sld2 and Sld3 by cyclin-dependent kinase. In mammals, RecQL4 and TopBP1 are excellent ortholog candidates for Sld2 and Dpb11, respectively. In this past year, three TopBP1-interacting proteins Treslin/Ticrr, GEMC1, and DUE-B have been identified in metazoans as possible functional orthologs of the yeast Sld3. To test this hypothesis, we carried out several complementation tests in fission yeast. The proteins were expressed at various levels in the temperature-sensitive sld3-10 mutant and in cells that lack endogenous Sld3. Our result showed that none of these metazoan proteins could rescue growth defect of the sld3 mutants. Although the result may have several interpretations, it is possible that the helicase activation in mammals has diverged in complexity during evolution from that in yeasts and may involve multiple players that interact with TopBP1.
authors.affiliation: Department of Biochemistry and Molecular Biology, Wright State University Boonshoft School of Medicine, Dayton, OH 45435, USA.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
authors.forename: Elaine
authors.initials: E
authors.lastname: Kim
authors.forename: Michael
authors.initials: M
authors.lastname: Leffak
authors.forename: Yong-Jie
authors.initials: YJ
authors.lastname: Xu
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D012568:Schizosaccharomyces / Q000235:genetics* / Q000254:growth & development*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C500359:DTD1 protein, human; C551026:GMNC protein, Xenopus; D029702:Schizosaccharomyces pombe Proteins; C496523:Sld3 protein, S pombe; C547407:TICRR protein, Xenopus; D029867:Xenopus Proteins