title: Punctuated evolution and transitional hybrid network in an ancestral cell cycle of fungi.
abstract: Although cell cycle control is an ancient, conserved, and essential process, some core animal and fungal cell cycle regulators share no more sequence identity than non-homologous proteins. Here, we show that evolution along the fungal lineage was punctuated by the early acquisition and entrainment of the SBF transcription factor through horizontal gene transfer. Cell cycle evolution in the fungal ancestor then proceeded through a hybrid network containing both SBF and its ancestral animal counterpart E2F, which is still maintained in many basal fungi. We hypothesize that a virally-derived SBF may have initially hijacked cell cycle control by activating transcription via the cis-regulatory elements targeted by the ancestral cell cycle regulator E2F, much like extant viral oncogenes. Consistent with this hypothesis, we show that SBF can regulate promoters with E2F binding sites in budding yeast.
authors.affiliation: Department of Biology, Duke University, Durham, United States.|Center for Genomic and Computational Biology, Duke University, Durham, United States.
authors.forename: Edgar M
authors.identifier: 0000-0002-5518-5933
authors.initials: EM
authors.lastname: Medina
authors.affiliation: Department of Biology, Stanford University, Stanford, United States.
authors.forename: Jonathan J
authors.identifier: 0000-0001-7311-0313
authors.initials: JJ
authors.lastname: Turner
authors.affiliation: Center for Genomic and Computational Biology, Duke University, Durham, United States.|Department of Biostatistics and Bioinformatics, Duke University, Durham, United States.
authors.forename: Raluca
authors.identifier: 0000-0002-6404-6556
authors.initials: R
authors.lastname: Gordân
authors.affiliation: Department of Biology, Stanford University, Stanford, United States.
authors.forename: Jan M
authors.identifier: 0000-0001-8420-6820
authors.initials: JM
authors.lastname: Skotheim
authors.affiliation: Department of Biology, Duke University, Durham, United States.|Center for Genomic and Computational Biology, Duke University, Durham, United States.
authors.forename: Nicolas E
authors.identifier: 0000-0003-3940-3432
authors.initials: NE
authors.lastname: Buchler
mesh_terms: D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D005658:Fungi / Q000166:cytology* / Q000235:genetics* / Q000502:physiology; D022761:Gene Transfer, Horizontal; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D014157:Transcription Factors
keywords: S. cerevisiae; cell cycle; chytrid; computational biology; evolution; evolutionary biology; fungi; genomics; horizontal gene transfer; systems biology; virus