Comparative in-silico analysis of the interactions between Ultrabithorax and its putative cofactors across different insect groups.

Abstract

In dipterans, the Hox protein Ultrabithorax (Ubx) specifies haltere fate in the third thoracic segment by repressing wing fate. While orthologues of Ubx are expressed in other insects such as Apis (Hymenoptera), Bombyx (Lepidoptera) and Tribolium (Coleoptera), it specifies haltere only in flies. The underlying cause behind this is differential regulation of target genes. Previous studies have shown that in-vitro all Hox proteins bind to similar ‘AT’ rich DNA sequence with similar affinity but in-vivo are very specific towards their target genes. Interaction with co-transcription factors can achieve this in-vivo specificity. Ubx is known to be interacting with other partner proteins to regulate the expression of its target genes differentially, and the interaction can be different in different insect species. There are various ways by which Ubx can regulate its target genes one of which is by direct physical interaction with the co-factor proteins. The current study aims at the direct physical interaction between Ubx and its cofactors in species of Drosophila in comparison with other species like Tribolium castaneum, Apis mellifera and Bombyx mori. This study includes prediction of interactions between Ubx and cofactors and identification of structural constraints on their binding sites using homology modeling. Later Based on the separation of binding sites of Ubx and a putative co-transcription factor in various species, we can comment on the evolution of Ubx-cofactor interactions that mediate gene regulation across different insect species. This can help in understanding the evolution of Ubx- cofactor interaction.