Generation of transgenic flies to uncover the role of the intrinsically disordered regions in transcriptional regulation using Drosophila melanogaster transcription factor Bicoid

Abstract

Multicellular organisms develop from a single cell into a complex organism. Their development is strictly controlled by transcription factors that control the gene expression in a context-dependent manner, so that each gene is expressed at the right time and place. The specificity of transcription factors is determined mainly by their DNA-binding domains; however, their activity and interaction with DNA, proteins, and small molecules are modified by the effector domains (EDs). The EDs are generally low-complexity regions with high flexibility, often intrinsically disordered. Intrinsically disordered regions (IDRs), with their flexible and adaptable nature, help navigate protein activity in a context-dependent manner. The maternal morphogen Bicoid is a transcription factor responsible for the anterior development of Drosophila melanogaster embryos that regulates the expression of hundreds of genes responsible for Drosophila segmentation. It is absolutely required for embryo development and its absence results in the replacement of anterior structures by posterior ones. It consists of a 60 amino acid long structured homeodomain (HD) flanked by IDRs on both amino- and carboxyl termini. Through full Bicoid and HD swap experiments between D.melanogaster, Lucilia sericata, and Calliphora vicina, we found disordered EDs are required for Bicoid's full developmental functions. We used the Drosophila genetic manipulation tool recombinase-mediated cassette exchange to generate Bicoid ED mutant flies. We aim to elucidate the role of IDRs in regulating the activity of Bicoid via phenotypical and molecular analyses.