Evolution and Diversity of Semaphorins and Plexins in Choanoflagellates

• DOI: 10.1093/gbe/evab035
• Publication Date: 2021-02-23T12:17:23Z
• Authors: Chrystian Junquei...; Júlia Silva Ladeira; Theodore Hannah; Roberto J Pedroso...; Priscila V Zabala...; Karla Yotoko; Hongyan Zou; Roland H Friedel
• Keywords: Plexin

Abstract Semaphorins and plexins are cell surface ligand/receptor proteins that affect cytoskeletal dynamics in metazoan cells. Interestingly, they also present Choanoflagellata, a class of unicellular heterotrophic flagellates forms the phylogenetic sister group to Metazoa. Several members choanoflagellates capable forming transient colonies, whereas others reside solitary inside exoskeletons; their molecular diversity is only beginning emerge. Here, we surveyed genomics data from 22 choanoflagellate species detected semaphorin/plexin pairs 16 species. Choanoflagellate semaphorins (Sema-FN1) contain several domain features distinct semaphorins, including an N-terminal Reeler may facilitate dimer stabilization, array fibronectin type III domains, variable serine/threonine-rich potential site for O-linked glycosylation, SEA can undergo autoproteolysis. In contrast, (Plexin-1) harbor arrangement largely identical plexins. Both Sema-FN1 Plexin-1 short homologous motif near C-terminus, likely associated with shared function. Three-dimensional models revealed highly conserved structural architecture as compared plexins, similar predicted conformational changes segment involved activation intracellular Ras-GAP domain. The absence did not appear correlate versus colonial lifestyle or ecological factors such fresh salt water environment. Together, our findings support mechanism regulating multicellular organisms.