RESUMO
Transvection is a phenomenon of interallelic communication in which enhancers can activate a specific promoter located on a homologous chromosome. Insulators play a significant role in ensuring functional interactions between enhancers and promoters. In the presented work, we created a model where two or three copies of the insulator are located next to enhancers and promoters localized on homologous chromosomes. Using the Su(Hw) insulator as a model, we showed that the functional interaction between a pair of insulators promotes enhancer-promoter trans-interactions. The interaction between the three insulators, on the contrary, can lead to the formation of chromatin loops that sterically hinder the full enhancer-promoter interaction. The results of the work suggest the participation of insulators in the regulation of homologous chromosome pairing and in communication between distant genomic loci.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Elementos Facilitadores Genéticos , Elementos Isolantes , Regiões Promotoras Genéticas , Animais , Drosophila melanogaster/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Elementos Isolantes/genética , Proteínas Repressoras/metabolismo , Proteínas Repressoras/genética , Cromatina/metabolismo , Cromatina/genéticaRESUMO
In Drosophila, the BEAF-32, Z4/putzig, and Chriz/Chromator proteins colocalize in the interbands of polytene chromosomes. It was assumed that these proteins can form a complex that affects the structure of chromatin. However, the mechanism of the formation of such a complex has not been studied. We have proved for the first time that the BEAF-32, Z4/putzig, and Chriz/Chromator proteins interact directly with each other and localized the protein domains that provide multiple protein-protein interactions. Based on the data obtained, we developed a model of the mechanism of the formation the BEAF/Z4/Chriz complex and its recruitment to chromatin.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Proteínas do Olho/metabolismo , Proteínas Associadas à Matriz Nuclear/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Cromatina/genética , Proteínas de Ligação a DNA/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Proteínas do Olho/genética , Proteínas Associadas à Matriz Nuclear/genética , Cromossomos Politênicos , Domínios e Motivos de Interação entre ProteínasRESUMO
Earlier, we showed in a model system of the yellow gene of D. melanogaster that an increase in the EAST protein concentration leads to repression in bristles, the mechanism of which remained obscure. In this study, an inverted repeat was localized by genetic methods in the long terminal repeat (LTR) sequence of the MDG4 retrotransposon. This repeat includes the binding site for the Mad protein-the key component of the of TGF-ß/BMP signaling cascade. The results of this work suggest that the Mad protein recruits to chromatin a regulatory complex that functionally interacts with the EAST protein. This complex either itself suppresses the yellow gene expression in bristles or moves the transgene to the nuclear regions with a high concentration of transcription repression factors.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Retroelementos/genética , Sequências Repetidas Terminais/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica/genética , Animais , Sequência de Bases , Sítios de Ligação , Drosophila melanogaster/metabolismoRESUMO
The structure of the new enhancer En1A of the 1A region of the X chromosome of D. melanogaster was investigated. Two distinct regulatory elements were found. The first element is responsible for transcription activation, and the second element provides specific interaction with the promoter of the yellow gene. The findings support the hypothesis of a modular structure for enhancers, including certain sequences that bind transcription activators and special communication elements providing long-distance enhancer-promoter interaction.
RESUMO
This study is devoted to clarifying the role of Mod(mdg4)-67.2 and Su(Hw) proteins in the interaction between Su(Hw)-dependent insulator complexes and identifying the specific domains of the Su(Hw) protein required for insulation or mutual neutralization of insulators. Using genetic techniques and experiments in yeast two-hybrid system, we have demonstrated that the zinc finger domain of the Su(Hw) protein is involved in forming a functional insulator complex and cannot be replaced with the DNA-binding domain of the GAL4 protein.