Functional cooperation between AAA-ATPase domain and a bromodomain.

A functional cooperation between an AAA type ATPase domain and a bromodomain has been evidenced. These two domains were identified and their activity tested in a yet uncharacterized factor, named Atad2, whose two-domain configuration remained highly conserved during evolution. In human and mouse, Atad2 is most abundantly expressed in testis and in the mouse. It has also been detected in post-meiotic stages and in mature spermatozoa. The AAA-ATPase domain was found necessary for protein multimerization and high affinity binding to acetylated nucleosomes by its bromodomain. The binding was found specific to acetylated histone H4 tail with a critical role for the acetylated K5 position. In vivo studies show that Atad2 behaves as a general repressor of transcription and possesses a chromatin “freezing” activity. Finally, we demonstrate that the induction of apoptosis leads to an early degradation of Atad2, which probably facilitates the action of apoptotic factors by increasing chromatin dynamics. The experimental design includes 6 slides, corresponding to 3 experimental comparisons, in dye-swap. Each comparison corresponds is done on a specific cell line (A549, SAOS or H1299), treated with a siRNA against Atad2 or against a control siRNA.