Reconstructing the evolutionary history and neofunctionalization of the ZAD-Znf chromatin regulator dwg
Authors: Jack Jurmu 1,2; Andrew Arsham 1,2
Affiliations: 1) Bemidji State University; 2) North Hennepin Community College
Keywords: a. genome evolution; j. epigenetics
The ZAD-Znf family of genes is evolutionarily dynamic, expanding sporadically across insect lineages via duplication and retrotransposition. The family is characterized by the presence of a conserved N-terminal zinc-coordinating ZAD domain upstream of anywhere from one to over a dozen grouped C2H2 zinc finger domains, connected by a poorly defined “linker” domain. New or fast-evolving ZAD-Znf genes can become essential through neofunctionalization. For example, nicknack and oddjob, two genes within a cluster of five ZAD-Znf paralogs, are essential in Drosophila melanogaster and have recently gained a heterochromatin regulatory function. Deformed wings (dwg, aka zeste-white5 or zw5) and CG2712 are neighboring and paralogous ZAD-Znf genes on the X chromosome of D. melanogaster. Protein sequence analysis suggests that both have acquired new functions within the last 5 million years. While dwg plays an essential role regulating insulators and enhancers in development, little is known about its non-essential near neighbor CG2712. In collaboration with the Genomics Education Partnership, we annotated the coding sequences of the two genes in D. melanogaster and other Drosophilid lineages diverging up to 40 million years ago. We compared domain and sequence architecture in order to reconstruct their evolutionary history and investigate their recent neofunctionalization.