Hos2 and Set3 Promote Integration of Ty1 Retrotransposons at tRNA Genes in Saccharomyces cerevisiae

Abstract

The yeast LTR retrotransposon Ty1 integrates preferentially into regions upstream of tRNA genes. The chromatin structure of transcriptionally active tRNA genes is known to be important for Ty1 integration, but specific chromatin factors that enhance integration at tRNA genes have not been identified. Here we report that the histone deacetylase, Hos2, and the Trithorax-group protein, Set3, both components of the Set3 complex (Set3C), enhance transposition of chromosomal Ty1 elements by promoting integration into the upstream region of tRNA genes. Deletion of HOS2 or SET3 reduced the mobility of a chromosomal Ty1his3AI element about sevenfold. Despite the fact that Ty1his3AI RNA, total Ty1 RNA, and total Ty1 cDNA levels were not reduced in hos2D or set3D mutants, transposition of endogenous Ty1 elements into the upstream regions of tRNAGly genes was substantially decreased. Furthermore, when equivalent numbers of Ty1HIS3 mobility events launched from a pGAL1:Ty1his3AI plasmid were analyzed, only one-quarter to one-half as many were found upstream of tRNAGly genes in a hos2D or set3D mutant than in a wild-type strain. Chromatin immunoprecipitation analysis revealed that Hos2 is physically associated with tRNA genes. Taken together, our results support the hypothesis that Hos2 and Set3 function at tRNA genes to promote Ty1 integration.

The Tig1 Histone Deacetylase Complex Regulates Infectious Growth in the Rice Blast Fungus Magnaporthe oryzae

“…TIG1 and its orthologs are conserved from yeast to human (Pijnappel et al, 2001;Mou et al, 2006). TIG1 shares higher similarity with mammalian TBL1 than with yeast SIF2.…”

“…SMRT proteins have an N-terminal domain that binds to nuclear receptors and a C-terminal region that interacts with HDACs. In yeast, Sif2 is a component of the Set3 HDAC complex that consists of Sif2, Hos2, Set3, Snt1, Hst1, Hos4, and Cpr1 (Pijnappel et al, 2001;Cerna and Wilson, 2005;Mou et al, 2006). Several of these proteins are conserved from yeast to human.…”

“…Table 3 lists proteins that were copurified with the TIG1-3xFLAG fusion. MGG_09174.5, MGG_01663.5, MGG_02488.5, MGG_10447.5, and MGG_05727.5 (Table 3) are orthologous to yeast SNT1, HOS2, HST1, CPR1, and HOS4, respectively, which are members of the Set3 complex (Pijnappel et al, 2001;Mou et al, 2006). They were consistently identified as TIG1-interacting genes in four independent biological replicates.…”

Proliferation and copy number variation of BEL-like long terminal repeat retrotransposons within the Diabrotica virgifera virgifera genome

“…e l s e v i e r . c o m / l o c a t e / g e n e eukaryotic genomes suggests target-site specificity (Kim et al, 1998 (Bachman et al, 2005;Mou et al, 2006;Yieh et al, 2000Yieh et al, , 2002. Movement of TEs within a genome can change chromosome structure (Eichler and Sankoff, 2003;Feschotte and Pritham, 2007;Kidwell and Lisch, 2001) and modulate the expression of nearby protein coding genes (Feschotte, 2008).…”

Insulator and Ovo Proteins Determine the Frequency and Specificity of Insertion of the gypsy Retrotransposon in Drosophila melanogaster

“…A number of examples involving integrases from yeast LTR retrotransposons have also shown that retroviral-like integrases have evolved to acquire strong site-specific integration properties (Sandmeyer 2003;Zhu et al 2003;Brady et al 2008;Gao et al 2008). For example, the integration of Saccharomyces cerevisiae retrotransposons Ty1 and Ty3 is associated with RNA polymerase III transcription (Yieh et al 2000;Bachman et al 2005;Mou et al 2006) and the Tf1 retrotransposon from Schizosaccharomyces pombe integrates near RNA polymerase II promoters (Singleton and Levin 2002;Bowen et al 2003). In other examples, transposable elements are targeted to heterochromatic sites by tethering mechanisms involving interactions between the integrase and DNA binding proteins.…”