title: The bromodomain protein LEX-1 acts with TAM-1 to modulate gene expression in C. elegans.
abstract: In many organisms, repetitive DNA serves as a trigger for gene silencing. However, some gene expression is observed from repetitive genomic regions such as heterochromatin, suggesting mechanisms exist to modulate the silencing effects. From a genetic screen in C. elegans, we have identified mutations in two genes important for expression of repetitive sequences: lex-1 and tam-1. Here we show that lex-1 encodes a protein containing an ATPase domain and a bromodomain. LEX-1 is similar to the yeast Yta7 protein, which maintains boundaries between silenced and active chromatin. tam-1 has previously been shown to encode a RING finger/B-box protein that modulates gene expression from repetitive DNA. We find that lex-1, like tam-1, acts as a class B synthetic multivulva (synMuv) gene. However, since lex-1 and tam-1 mutants have normal P granule localization, it suggests they act through a mechanism distinct from other class B synMuvs. We observe intragenic (interallelic) complementation with lex-1 and a genetic interaction between lex-1 and tam-1, data consistent with the idea that the gene products function in the same biological process, perhaps as part of a protein complex. We propose that LEX-1 and TAM-1 function together to influence chromatin structure and to promote expression from repetitive sequences.
authors.affiliation: Department of Molecular Genetics, Ohio State University, 938 Biological Sciences Building, 484 West 12th Avenue, Columbus, OH 43210, USA.
authors.forename: Rong-Jeng
authors.initials: RJ
authors.lastname: Tseng
authors.forename: Kristin R
authors.initials: KR
authors.lastname: Armstrong
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
authors.forename: Helen M
authors.initials: HM
authors.lastname: Chamberlin
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D018797:Cell Cycle Proteins; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D006579:Heterozygote; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000502:physiology*; D010641:Phenotype; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C402463:TAM-1 protein, C elegans; D004247:DNA; D000251:Adenosine Triphosphatases; C524809:Lex-1 protein, C elegans