Nature Publication - CTVR researchers have crystallized NinaB

CTVR researchers have crystallized the visual chromophore-producing “isomerooxygenase”, NinaB, a key enzyme in the de novo generation of 11-cis-retinal for invertebrate vision. NinaB operates similarly to another protein of major importance for human vision, RPE65, and both belong to the carotenoid cleavage dioxygenase family. There has been a long-standing interest in the vision science field to understand the commonalities and differences in how these two proteins function. Having obtained an atomic-resolution picture of NinaB, researchers were able to resolve a key conserved region in animal CCDs that had eluded characterization in structural studies of RPE65, thereby providing a new model to understand mutations associated with devastating RPE65-associated retinal diseases. The researchers discovered key residues responsible for NinaB’s trans-cis isomerase activity, which differed from those used by RPE65 to achieve the same function. The researchers inferred that two distinct evolutionary pathways were taken to achieve 11-cis-retinal biosynthetic activity in the RPE65 and NinaB enzyme lineages. The study “Carotenoid cleavage enzymes evolved convergently to generate the visual chromophore” was published in Nature Chemical Biology. Authors of the study are Yasmeen J. Solano, Michael P. Everett, Kelly S. Dang, Jude Abueg, and Philip D. Kiser, in the Department of Physiology and Biophysics and the Department of Ophthalmology at the University of California, Irvine.