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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.

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Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.
Department of Molecular Biology, Princeton University, New Jersey 08544.
Department of Genetics and Evolution, University of 1205 Geneva. Switzerland.
Centre for Cellular and Molecular Biology, Hyderabad 500007, India.
Department of Molecular Biology, Princeton University, New Jersey 08544


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.


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

[Available on 2019-10-01]
[Indexed for MEDLINE]

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