title: Identification of nucleic acid binding residues in the FCS domain of the polycomb group protein polyhomeotic.
abstract: Polycomb group (PcG) proteins maintain the silent state of developmentally important genes. Recent evidence indicates that noncoding RNAs also play an important role in targeting PcG proteins to chromatin and PcG-mediated chromatin organization, although the molecular basis for how PcG and RNA function in concert remains unclear. The Phe-Cys-Ser (FCS) domain, named for three consecutive residues conserved in this domain, is a 30-40-residue Zn(2+) binding motif found in a number of PcG proteins. The FCS domain has been shown to bind RNA in a non-sequence specific manner, but how it does so is not known. Here, we present the three-dimensional structure of the FCS domain from human Polyhomeotic homologue 1 (HPH1, also known as PHC1) determined using multidimensional nuclear magnetic resonance methods. Chemical shift perturbations upon addition of RNA and DNA resulted in the identification of Lys 816 as a potentially important residue required for nucleic acid binding. The role played by this residue in Polyhomeotic function was demonstrated in a transcription assay conducted in Drosophila S2 cells. Mutation of the Arg residue to Ala in the Drosophila Polyhomeotic (Ph) protein, which is equivalent to Lys 816 in HPH1, was unable to repress transcription of a reporter gene to the level of wild-type Ph. These results suggest that direct interaction between the Ph FCS domain and nucleic acids is required for Ph-mediated repression.
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center at San Antonio, MSC 7760, San Antonio, Texas 78229-3990, United States.
authors.forename: Renjing
authors.initials: R
authors.lastname: Wang
authors.forename: Udayar
authors.initials: U
authors.lastname: Ilangovan
authors.forename: Belinda Z
authors.initials: BZ
authors.lastname: Leal
authors.forename: Angela K
authors.initials: AK
authors.lastname: Robinson
authors.forename: Barbara T
authors.initials: BT
authors.lastname: Amann
authors.forename: Corey V
authors.initials: CV
authors.lastname: Tong
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Berg
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Hinck
authors.forename: Chongwoo A
authors.initials: CA
authors.lastname: Kim
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004330:Drosophila / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D019906:Nuclear Magnetic Resonance, Biomolecular; D009698:Nucleoproteins / Q000737:chemistry* / Q000378:metabolism; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009698:Nucleoproteins; C491239:PHC1 protein, human; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C072820:ph-d protein, Drosophila; D004247:DNA; D063150:Polycomb Repressive Complex 1