ABSTRACT
The Penelope element is the key element responsible for mobilization of other transposable elements in the course of hybrid dysgenesis in Drosophila virilis. Penelope has an unusually complex, highly variable organization in all studied species of the virlis group. Thc BRIDGE1 element from the fish Fugu rubripes is homologous to Penelope, and database searches detected additional homologous sequences among Expressed Sequence Tags from the flatworm Schistosoma mansonii and the nematode Ancylostoma caninum. Phylogenetic analysis shows that the reverse transcriptase of the Penelope group does not belong to any of the characterized major retroelement lineages, but apparently represents a novel branch of non-LTR retroelements. Sequence profile analysis results in the prediction that the C-terminal domain of the Penelope polyprotein is an active endonuclease related to intron-encoded endonucleases and the bacterial repair endonuclease UvrC, which could function as an integrase. No retroelements containing a predicted endonuclease of this family have been described previously. Phylogenetic analysis of Penelope copies isolated from several species of the virilis group reveals two subfamilies of Penelope elements, one of which includes full-length copies whose nucleotide sequences are almost identical, whereas the other one consists of highly diverged defective copies. Phylogenetic analysis of Penelope suggests both vertical transmission of the element and probable horizontal transfers. These findings support the notion that Penelope invasions occurred repeatedly in the evolution of the virilis group.
Subject(s)
Drosophila/genetics , Endodeoxyribonucleases , Evolution, Molecular , Retroelements/genetics , Amino Acid Sequence , Animals , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Drosophila/enzymology , Endonucleases/chemistry , Endonucleases/genetics , Escherichia coli Proteins , Integrases/chemistry , Integrases/genetics , Introns/genetics , Molecular Sequence Data , Mutation/genetics , Phylogeny , RNA-Directed DNA Polymerase/chemistry , RNA-Directed DNA Polymerase/genetics , Sequence Alignment , Sequence Homology, Amino AcidABSTRACT
The GATA factor Pannier activates the achaete-scute (ASC) proneural complex through enhancer binding and provides positional information for sensory bristle patterning in Drosophila. Chip was previously identified as a cofactor of the dorsal selector Apterous, and we show here that both Apterous and Chip also regulate ASC expression. Chip cooperates with Pannier in bridging the GATA factor with the HLH Ac/Sc and Daughterless proteins to allow enhancer-promoter interactions, leading to activation of the proneural genes, whereas Apterous antagonizes Pannier function. Within the Pannier domain of expression, Pannier and Apterous may compete for binding to their common Chip cofactor, and the accurate stoichiometry between these three proteins is essential for both proneural prepattern and compartmentalization of the thorax.
Subject(s)
Body Patterning , DNA-Binding Proteins/metabolism , Drosophila Proteins , Drosophila/genetics , Insect Proteins/metabolism , Nervous System/embryology , Nuclear Proteins/metabolism , Transcription Factors/metabolism , Amino Acid Sequence , Animals , Basic Helix-Loop-Helix Transcription Factors , Crosses, Genetic , Drosophila/embryology , Ethyl Methanesulfonate , Female , Helix-Loop-Helix Motifs , Male , Mechanoreceptors/physiology , Molecular Sequence Data , Mutagenesis , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Protein Structure, Secondary , Sequence Alignment , Sequence Homology, Amino Acid , Thorax , Zinc FingersABSTRACT
Mammalian TIF1alpha and TIF1beta (KAP-1/KRIP-1) are related transcriptional intermediary factors that possess intrinsic silencing activity. TIF1alpha is believed to be a euchromatic target for liganded nuclear receptors, while TIF1beta may serve as a co-repressor for the large family of KRAB domain-containing zinc finger proteins. Here, we report an association of TIF1beta with both heterochromatin and euchromatin in interphase nuclei. Co-immunoprecipitation of nuclear extracts shows that endogenous TIF1beta, but not TIF1alpha, is associated with members of the heterochromatin protein 1 (HP1) family. However, in vitro, both TIF1alpha and TIF1beta interact with and phosphorylate the HP1 proteins. This interaction involves a conserved amino acid motif, which is critical for the silencing activity of TIF1beta but not TIF1alpha. We further show that trichostatin A, an inhibitor of histone deacetylases, can interfere with both TIF1 and HP1 silencing. The silencing activity of TIF1alpha appears to result chiefly from histone deacetylation, whereas that of TIF1beta may be mediated via both HP1 binding and histone deacetylation.
Subject(s)
Chromosomal Proteins, Non-Histone/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Regulation , Histones/metabolism , Nuclear Proteins/metabolism , Repressor Proteins/metabolism , Transcription Factors/metabolism , Amino Acid Sequence , Animals , Cell Line , Cell Nucleus/metabolism , Chromatin/metabolism , Chromobox Protein Homolog 5 , Chromosomal Proteins, Non-Histone/isolation & purification , Cloning, Molecular , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/genetics , Enzyme Inhibitors/pharmacology , Euchromatin , Heterochromatin/metabolism , Histone Deacetylase Inhibitors , Histone Deacetylases/metabolism , Humans , Hydroxamic Acids/pharmacology , Mice , Molecular Sequence Data , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Phosphorylation , Recombinant Fusion Proteins , Repressor Proteins/chemistry , Repressor Proteins/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Transcription Factors/chemistry , Transcription Factors/genetics , Transcription, Genetic , Transcriptional Activation , Tripartite Motif-Containing Protein 28 , Zinc FingersABSTRACT
The esterase S gene (estS) of Drosophila virilis is specifically expressed in the ejaculatory bulbs of males. Its sequencing shows similarities between estS product and other esterases of different origin. The transcription of estS in ejaculatory bulbs is at least 2 orders of magnitude higher than in other tissues of males. Two promoters, P1 (distal) and P2 (proximal), and two different transcripts were identified. The promoter P2 is used much more efficiently, and in a stringent, tissue-specific manner. The transcription from P1 takes place in different tissues and stages of development of D. virilis. However, the mRNA transcribed from P1 seems to be inactive in translation as there are three open-reading frames (ORF) between P1 and P2, which may block the translation in P1 initiated mRNA. Insertion of sequence containing the three ORFs into the 5' untranslated region of the CAT gene strongly inhibited expression of CAT. Point mutations destroying the three ORFs completely eliminate the inhibitory effect. Hence tissue-specific expression of the estS gene may depend on control at the level of transcription, promoter selection and translation.
Subject(s)
Carboxylic Ester Hydrolases/genetics , Drosophila Proteins , Drosophila/genetics , Gene Expression Regulation , Amino Acid Sequence , Animals , Base Sequence , Carboxylesterase , Cell Line , Chickens , Chloramphenicol O-Acetyltransferase/genetics , Codon , Female , Male , Molecular Sequence Data , Open Reading Frames , Point Mutation , Promoter Regions, Genetic , RNA, Messenger/genetics , RNA, Messenger/metabolism , Tissue Distribution , Transcription, Genetic , TransfectionABSTRACT
The transcription initiation region of the gene for tissue-specific esterase S of D. virilis has been analysed. By means of high-resolution S1-mapping we located a set of transcription initiation points, two of them being major ones. The position of the major start points, but not the efficiency of their usage, does not depend on age, sex or strain of the flies. The transcription initiation region is sequenced. The region contains various motifs characteristic for eukaryotic promoters.
