A network of interacting transcriptional regulators involved in Drosophila neural fate specification revealed by the yeast two-hybrid system.
Neural fate specification in Drosophila is promoted by the products of the proneural genes, such as those of the achaete-scute complex, and antagonized by the products of the Enhancer of split [E(spl)] complex, hairy, and extramacrochaetae. As all these proteins bear a helix-loop-helix (HLH) dimerization domain, we investigated their potential pairwise interactions using the yeast two-hybrid system. The fidelity of the system was established by its ability to closely reproduce the already documented interactions among Da, Ac, Sc, and Extramacrochaetae. We show that the seven E(spl) basic HLH proteins can form homo- and heterodimers inter-se with distinct preferences. We further show that a subset of E(spl) proteins can heterodimerize with Da, another subset can heterodimerize with proneural proteins, and yet another with both, indicating specialization within the E(spl) family. Hairy displays no interactions with any of the HLH proteins tested. It does interact with the non-HLH protein Groucho, which itself interacts with all E(spl) basic HLH proteins, but with none of the proneural proteins or Da. We investigated the structural requirements for some of these interactions by site-specific and deletion mutagenesis.
Alifragis
P
P
Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Hellas, and Department of Biology, University of Crete, Heraklion, Greece.
Poortinga
G
G
Parkhurst
S M
SM
Delidakis
C
C
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D015966:Gene Expression Regulation, Fungal; D018257:Helix-Loop-Helix Motifs; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D051792:Basic Helix-Loop-Helix Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; C489235:hairy protein, Drosophila; C061841:hairy protein, insect