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Genetics. 2018 Oct;210(2):573-585. doi: 10.1534/genetics.118.301259. Epub 2018 Aug 6.

The BEN Domain Protein Insensitive Binds to the Fab-7 Chromatin Boundary To Establish Proper Segmental Identity in Drosophila.

Author information

1
Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.
2
Department of Molecular Biology, Princeton University, New Jersey 08544.
3
Department of Genetics and Evolution, University of 1205 Geneva. Switzerland.
4
Centre for Cellular and Molecular Biology, Hyderabad 500007, India.
5
Department of Molecular Biology, Princeton University, New Jersey 08544 pschedl@princeton.edu.

Abstract

Boundaries (insulators) in the Drosophila bithorax complex (BX-C) delimit autonomous regulatory domains that orchestrate the parasegment (PS)-specific expression of the BX-C homeotic genes. The Fab-7 boundary separates the iab-6 and iab-7 regulatory domains, which control Abd-B expression in PS11 and PS12, respectively. This boundary is composed of multiple functionally redundant elements and has two key functions: it blocks cross talk between iab-6 and iab-7 and facilitates boundary bypass. Here, we show that two BEN domain protein complexes, Insensitive and Elba, bind to multiple sequences located in the Fab-7 nuclease hypersensitive regions. Two of these sequences are recognized by both Insv and Elba and correspond to a CCAATTGG palindrome. Elba also binds to a related CCAATAAG sequence, while Insv does not. However, the third Insv recognition sequences is ∼100 bp in length and contains the CCAATAAG sequence at one end. Both Insv and Elba are assembled into large complexes (∼420 and ∼265-290 kDa, respectively) in nuclear extracts. Using a sensitized genetic background, we show that the Insv protein is required for Fab-7 boundary function and that PS11 identity is not properly established in insv mutants. This is the first demonstration that a BEN domain protein is important for the functioning of an endogenous fly boundary.

KEYWORDS:

Abdominal B; BEN DNA-binding domain; Elba; Fab-7; Insensitive; bithorax; boundary; chromatin; insulator; parasegment identity

PMID:
30082280
PMCID:
PMC6216583
[Available on 2019-10-01]
DOI:
10.1534/genetics.118.301259

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