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Binding of Trithorax and Polycomb proteins to the bithorax complex: dynamic changes during early Drosophila embryogenesis
Author(s) -
Orlando Valerio,
Jane Esther P.,
Chinwalla Vandana,
Harte Peter J.,
Paro Renato
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.17.5141
Subject(s) - biology , polycomb group proteins , ultrabithorax , chromatin , drosophila embryogenesis , promoter , genetics , transcription (linguistics) , heterochromatin , transcription factor , dna binding protein , drosophila melanogaster , blastoderm , euchromatin , homeotic gene , gene , repressor , embryogenesis , gene expression , linguistics , philosophy
In Drosophila , the maintenance of developmentally important transcription patterns is controlled at the level of chromatin structure. The Polycomb group (PcG) and trithorax group (trxG) genes encode proteins involved in chromatin remodelling. PcG genes have been proposed to act by packaging transcriptional repressed chromosomal domains into condensed heterochromatin‐like structures. Some of the trxG proteins characterized so far are members of chromatin opening complexes (e.g. SWI/SNF and GAGA/NURF) which facilitate binding of transcription factors and components of the basal transcriptional machinery. Genetic and biochemical data suggest that these two groups of regulatory factors may act through a common set of DNA elements. In the present study, we have investigated the binding of Trithorax (TRX) and Polycomb (PC) protein in the bithorax complex (BX‐C) during embryogenesis. In addition, we have identified the minimal fragments from the Ultrabithorax (Ubx) regulatory region that are capable of recruiting TRX to chromosomal sites containing them. Comparative analysis of the binding of the two proteins shows that TRX and PC bind target sequences (PcG‐regulated elements, PREs) by cellular blastoderm, when BX‐C transcription begins. At the same stage, TRX but not PC is strongly associated with core promoters. Later, at germ band extension, the time of derepression in Polycomb mutants, PC binding is also detected outside core PREs and additionally binds to the fragments containing promoters.