Functional divergence of paralogous transcription factors supported the evolution of biomineralization in echinoderms
- Carnegie Mellon University, United States
Abstract
Alx1 is a pivotal transcription factor in a gene regulatory network that controls skeletogenesis throughout the echinoderm phylum. We performed a structure-function analysis of sea urchin Alx1 using a rescue assay and identified a novel, conserved motif (Domain 2) essential for skeletogenic function. The paralogue of Alx1, Alx4, was not functionally interchangeable with Alx1, but insertion of Domain 2 conferred robust skeletogenic function on Alx4. We used cross-species expression experiments to show that Alx1 proteins from distantly related echinoderms are not interchangeable, although the sequence and function of Domain 2 are highly conserved. We also found that Domain 2 is subject to alternative splicing and provide evidence that this domain was originally gained through exon extension. Our findings show that a gene duplication event permitted the functional specialization of a transcription factor through changes in exon-intron organization and thereby supported the evolution of a major morphological novelty.
Data availability
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SpBase:the sea urchin genome database and web sitePublicly available at spBase.org.
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Echinobase: an expanding resource for echinoderm genomic informationPublicly available at echinobase.org.
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Hemichordate genomes and deuterostome originsPublicly available at marinegenomics.oist.jp.
Article and author information
Author details
Charles A Ettensohn
Funding
National Science Foundation (IOS-1354973)
- Charles A Ettensohn
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Khor & Ettensohn
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Functional divergence of paralogous transcription factors supported the evolution of biomineralization in echinoderms
eLife 6:e32728.
https://doi.org/10.7554/eLife.32728
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