Fedotova, A., Aoki, T., Rossier, M., Mishra, R.K., Clendinen, C., Kyrchanova, O., Wolle, D., Bonchuk, A., Maeda, R.K., Mutero, A., Cleard, F., Mogila, V., Karch, F., Georgiev, P., Schedl, P. (2018). The BEN Domain Protein Insensitive Binds to the Fab-7 Chromatin Boundary To Establish Proper Segmental Identity in Drosophila.  Genetics 210(2): 573--585.

FBrf0240249

Research paper

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.

PMC6216583 (PMC) (EuropePMC)