Architectural protein Pita cooperates with dCTCF in organization of functional boundaries in Bithorax complex

• Published in: Development (Cambridge) Vol. 144; no. 14; pp. 2663 - 2672
• Main Authors: Kyrchanova, Olga, Zolotarev, Nikolay, Mogila, Vladic, Maksimenko, Oksana, Schedl, Paul, Georgiev, Pavel
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 15.07.2017
• Subjects: Animals; Animals, Genetically Modified; Binding sites; Boundaries; C gene; CCCTC-Binding Factor; Chromatin; Chromatin Immunoprecipitation; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Drosophila; Drosophila melanogaster - genetics; Drosophila melanogaster - growth & development; Drosophila melanogaster - metabolism; Drosophila Proteins - chemistry; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Functional morphology; Gene Expression Regulation, Developmental; Gene regulation; Genes, Homeobox; Genes, Insect; Insects; Mutation; Protein Interaction Domains and Motifs; Proteins; Repressor Proteins - chemistry; Repressor Proteins - genetics; Repressor Proteins - metabolism; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Zinc finger proteins; Chromatin organization; Zinc-finger transcription factors; Insulator; Architectural proteins; Protein-protein interactions
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.149815

Boundaries in the Bithorax complex (BX-C) of delimit autonomous regulatory domains that drive parasegment-specific expression of homeotic genes. BX-C boundaries have two crucial functions: they must block crosstalk between adjacent regulatory domains and at the same time facilitate boundary bypass. The C2H2 zinc-finger protein Pita binds to several BX-C boundaries, including and To study Pita functions, we have used a boundary replacement strategy by substituting modified DNAs for the boundary, which is located between the and regulatory domains. Multimerized Pita sites block crosstalk but fail to support regulation of (bypass). In the case of , we used a novel sensitized background to show that the two Pita-binding sites contribute to its boundary function. Although is from BX-C, it does not function appropriately when substituted for : it blocks crosstalk but does not support bypass. Mutation of the Pita site disrupts blocking activity and also eliminates dCTCF binding. In contrast, mutation of the dCTCF site does not affect Pita binding, and this mutant boundary retains partial function.