The BTB/POZ Domain of the Regulatory Proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) Interacts with the Novel Drosophila TAFII Factor BIP2/dTAFII155

Abstract

The BTB/POZ domain is an evolutionarily conserved protein-protein interaction domain present in the N-terminal region of numerous transcription factors involved in development, chromatin remodeling, and human cancers. This domain is involved in homomeric and heteromeric associations with other BTB/POZ domains. The Drosophila BTB/POZ proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) are developmentally regulated transcription factors which are involved in pattern formation along the proximo-distal axis of the leg and antenna, in the morphogenesis of the adult ovaries, and in the control of sexually dimorphic characters. We have identified partners of the BAB1 protein by using the two-hybrid system. The characterization of one of these proteins, called BIP2 for BAB Interacting Protein 2, is presented. BIP2 is a novel Drosophila TATA-box Protein Associated Factor (TAF(II)), also named dTAF(II)155. We show that the BTB/POZ domains of BAB1 and BAB2 are sufficient to mediate a direct interaction with BIP2/dTAF(II)155. This provides a direct link between these BTB/POZ transcription factors and the basal transcriptional machinery. We discuss the implications of the interaction between a BTB/POZ domain and a TAF(II) for the molecular mechanisms of transcriptional control mediated by BTB/POZ transcription factors.

Maternal RNAs encoding transcription factors for germline-specific gene expression in Drosophila embryos

“…TAFs have been known to act as specific coactivators by interacting with transcriptional activators, and TAFs contribute to promoter recognition and selectivity (Verrijzer et al, 1994;Burke and Kadonaga, 1997). BIP2 was first identified as a partner of the Bric à brac 2 (Bab2) protein (Pointud et al, 2001). BAB2 interacts with BIP2 via BTB/POZ domains, and these two proteins colocalize at transcriptionally active regions of polytene chromosomes (Pointud et al, 2001).…”

Drosophila BTB/POZ Domains of “ttk Group” Can Form Multimers and Selectively Interact with Each Other

“…10 A significant amount of data indicates that BTB domains are involved in the recruitment of non-BTB-containing regulator proteins. [11][12][13] Another set of experiments have shown that BTB domains of different proteins in some cases can specifically interact with each other, but it is unknown how such interactions proceed. Rarely, heterodimerization of two different BTBs has been observed.…”

Expression pattern of Gal4 enhancer trap insertions into the bric à brac locus generated by P element replacement

“…Bab2 was also shown to bind at discrete sites along polytene chromosomes (D. Godt, unpubl. data;Pointud et al, 2001), suggesting that Bab1 and Bab2 function as transcriptional regulators.…”

“…Both genes encode proteins with a BTB domain and a pipsqueak motif (Couderc et al, 2002), domains found in a number of transcriptional regulators (Collins, 2001;Lehmann, 1998). Both Bab1 and Bab2 are localized to the nucleus (Couderc et al, 2002;Godt and Laski, 1995;Godt et al, 1993) and interact with BIP2/ TAF II 155, a component of TFIID (Pointud et al, 2001). Bab2 was also shown to bind at discrete sites along polytene chromosomes (D. Godt, unpubl.…”