Tunicates Illuminate the Enigmatic Evolution of Chordate Metallothioneins by Gene Gains and Losses, Independent Modular Expansions, and Functional Convergences

Sara Calatayud, Mario Garcia-Risco, Òscar Palacios, Mercè Capdevila, Cristian Cañestro, Ricard Albalat*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)

Abstract

To investigate novel patterns and processes of protein evolution, we have focused in the metallothioneins (MTs), a singular group of metal-binding, cysteine-rich proteins that, due to their high degree of sequence diversity, still represents a "black hole"in Evolutionary Biology. We have identified and analyzed more than 160 new MTs in nonvertebrate chordates (especially in 37 species of ascidians, 4 thaliaceans, and 3 appendicularians) showing that prototypic tunicate MTs are mono-modular proteins with a pervasive preference for cadmium ions, whereas vertebrate and cephalochordate MTs are bimodular proteins with diverse metal preferences. These structural and functional differences imply a complex evolutionary history of chordate MTs-including de novo emergence of genes and domains, processes of convergent evolution, events of gene gains and losses, and recurrent amplifications of functional domains-that would stand for an unprecedented case in the field of protein evolution.

Original languageEnglish
Pages (from-to)4435-4448
Number of pages14
JournalMolecular Biology and Evolution
Volume38
Issue number10
DOIs
Publication statusPublished - 1 Oct 2021

Keywords

  • ascidians/thaliaceans/appendicularians
  • Chordata
  • metallothionein domains
  • metallothionein evolution
  • modular proteins
  • Tunicata

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