Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs

Benjamin Auxier*, Jaclyn Dee, Mary L. Berbee, Michelle Momany

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

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 possibly also 1B and 2. Group 5 septins were present in fungi but not in animals and whether they were present in the opisthokont ancestor was unclear. Protein homology folding showed that previously identified conserved septin motifs were all located near interface regions between the adjacent septin monomers. 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.

Original languageEnglish
Article number4
JournalBMC Evolutionary Biology
Volume19
Issue number1
DOIs
Publication statusPublished - 7 Jan 2019
Externally publishedYes

Keywords

  • Ancestral state reconstruction
  • Evolution
  • Gene tree-species tree reconciliation
  • Modelling
  • Opisthokont
  • Protein-protein interaction
  • Septin
  • Subunit

Fingerprint Dive into the research topics of 'Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs'. Together they form a unique fingerprint.

  • Cite this