Prod is a novel DNA-binding protein that binds to the 1.686 g/cm(3) 10 bp satellite repeat of Drosophila melanogaster

The proliferation disrupter (prod) gene of Drosophila melanogaster encodes a novel protein associated with centromeric chromosomal regions that is req uired for chromatin condensation and cell viability. We have examined the b inding of the Prod protein to DNA in vitro, Co-immunoprecipitation experime nts demonstrate that Prod is a DNA-binding protein that specifically recogn izes the 10 bp AGAATAACAT satellite repeat of D. melanogaster. Footprinting experiments show that the protein interacts with a 5-8 bp target sequence in each 10 bp repeat and suggest that it can mediate condensation of this s atellite into a superhelix. Gel retardation experiments indicate that Prod does not have a well defined DNA-binding domain and it binds the satellite in a co-operative manner, probably forming Prod multimers, Since Prod local izes to both heterochromatin and euchromatin in vivo, we discuss the possib ility that the ability of pre-existing euchromatic proteins to bind DNA in a co-operative manner, might be a prerequisite of satellite compaction and satellite amplification, thereby providing a basic factor in heterochromati n evolution.