title: Efficient detection of unpaired DNA requires a member of the rad54-like family of homologous recombination proteins.
abstract: Meiotic silencing by unpaired DNA (MSUD) is a process that detects unpaired regions between homologous chromosomes and silences them for the duration of sexual development. While the phenomenon of MSUD is well recognized, the process that detects unpaired DNA is poorly understood. In this report, we provide two lines of evidence linking unpaired DNA detection to a physical search for DNA homology. First, we have found that a putative SNF2-family protein (SAD-6) is required for efficient MSUD in Neurospora crassa. SAD-6 is closely related to Rad54, a protein known to facilitate key steps in the repair of double-strand breaks by homologous recombination. Second, we have successfully masked unpaired DNA by placing identical transgenes at slightly different locations on homologous chromosomes. This masking falls apart when the distance between the transgenes is increased. We propose a model where unpaired DNA detection during MSUD is achieved through a spatially constrained search for DNA homology. The identity of SAD-6 as a Rad54 paralog suggests that this process may be similar to the searching mechanism used during homologous recombination.
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Dilini A
authors.initials: DA
authors.lastname: Samarajeewa
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Pegan A
authors.initials: PA
authors.lastname: Sauls
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Sharp
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Smith
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211.
authors.forename: Hua
authors.initials: H
authors.lastname: Xiao
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Groskreutz
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Tyler L
authors.initials: TL
authors.lastname: Malone
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Boone
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Edwards
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211.
authors.forename: Patrick K T
authors.initials: PK
authors.lastname: Shiu
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790.
authors.forename: Erik D
authors.initials: ED
authors.lastname: Larson
authors.affiliation: School of Biological Sciences, Illinois State University, Normal, Illinois 61790 tmhammo@ilstu.edu.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hammond
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D003433:Crosses, Genetic; D004271:DNA, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D059765:Homologous Recombination / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008540:Meiosis; D016254:Mutagenesis, Insertional; D009492:Neurospora crassa / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013172:Spores, Fungal / Q000254:growth & development; D013489:Suppression, Genetic
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D012333:RNA, Messenger
keywords: RNA silencing; Rad54; chromosome pairing; homologous recombination; meiosis