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Data from: Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs

Cite this dataset

Auxier, Ben; Dee, Jacklyn; Berbee, Mary Lee; Momany, Michelle (2018). Data from: Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs [Dataset]. Dryad.


Background: Septins are cytoskeletal proteins important in cell division and in establishing and maintaining cell polarity. Although septins are found in various eukaryotes, septin genes had the richest history of duplication and diversification in the animals, fungi and protists that comprise opisthokonts. Opisthokont septin paralogs encode modular proteins that assemble into heteropolymeric higher order structures. The heteropolymers can create physical barriers to diffusion or serve as scaffolds organizing other morphogenetic proteins. How the paralogous septin modules interact to form heteropolymers is still unclear. Through comparative analyses, we hoped to clarify the evolutionary origin of septin diversity and to suggest which amino acid residues were responsible for subunit binding specificity. Results: Here we take advantage of newly sequenced genomes to reconcile septin gene trees with a species phylogeny from 22 animals, fungi and protists. Our phylogenetic analysis divided 120 septins representing the 22 taxa into seven clades (Groups) of paralogs. Suggesting that septin genes duplicated early in opisthokont evolution, animal and fungal lineages share septin Groups 1A, 4 and 2. Group 1B septins were present in animals and early diverging fungi but missing from Ascomycota and Basidiomycota. Protein homology folding showed that previously identified conserved septin motifs were all located near interface regions between the adjacent septin modules of a dimer. We found specific interface residues associated with each septin Group that are candidates for providing subunit binding specificity. Conclusions: This work reveals that duplication of septin genes began in an ancestral opisthokont more than a billion years ago and continued through the diversification of animals and fungi. Evidence for evolutionary conservation of ~49 interface residues will inform mutagenesis experiments and lead to improved understanding of the rules guiding septin heteropolymer formation and from there, to improved understanding of development of form in animals and fungi.

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