Meeting Abstract
Over the evolutionary span of ~450 million years, cephalopods have radiated into various ecological niches; this radiation is correlated with the structural divergence of tissues with optical function. These evolved optical devices include beam collimators, fiber-optic light guides, broadband reflectors, and dynamic directional mirrors. The reflectin-family proteins from which most of these diverse structures are assembled may be a cephalopod synapomorphy. Reflectins are an unusual, highly diverse family of apparently disordered proteins defined by a ~30 aa conserved motif that shows high conservation across decapod species, but also high polydispersity in individual species. Using RNASeq, mass spectrometry, and nucleotide substitution models, we characterized editing of reflectin transcripts in three tissues with eye-camouflaging function. Our transcriptome analysis of three distantly-related squid taxa reveals unprecedentedly high levels of RNA editing specifically of reflectin proteins, even given recent observations that cephalopods generally have very high levels of editing. Our mass spec evidence demonstrates that this editing at the RNA level in fact leads to massive physical polydispersity of reflectin proteins. Additionally, the RNA editing that occurs in reflectin proteins exhibits different patterns from the RNA editing in the cephalopod nervous system. The talk will also discuss hypotheses about the possible physicochemical roles of polydispersity in the evolved self-assembly of these proteins in the optical devices they inhabit.
