Kappé, G. and Purkiss, Andrew G. and Genesen, S.T. and Slingsby, Christine and Lubsen, N.H. (2010) Explosive expansion of βγ-Crystallin genes in the ancestral vertebrate. Journal of Molecular Evolution 71 (3), pp. 219-230. ISSN 0022-2844.
Abstract
In jawed vertebrates, βγ-crystallins are restricted to the eye lens and thus excellent markers of lens evolution. These βγ-crystallins are four Greek key motifs/two domain proteins, whereas the urochordate βγ-crystallin has a single domain. To trace the origin of the vertebrate βγ-crystallin genes, we searched for homologues in the genomes of a jawless vertebrate (lamprey) and of a cephalochordate (lancelet). The lamprey genome contains orthologs of the gnathostome βB1-, βA2- and γN-crystallin genes and a single domain γN-crystallin-like gene. It contains at least two γ-crystallin genes, but lacks the gnathostome γS-crystallin gene. The genome also encodes a non-lenticular protein containing βγ-crystallin motifs, AIM1, also found in gnathostomes but not detectable in the uro- or cephalochordate genome. The four cephalochordate βγ-crystallin genes found encode two-domain proteins. Unlike the vertebrate βγ-crystallins but like the urochordate βγ-crystallin, three of the predicted proteins contain calcium-binding sites. In the cephalochordate βγ-crystallin genes, the introns are located within motif-encoding region, while in the urochordate and in the vertebrate βγ-crystallin genes the introns are between motif- and/or domain encoding regions. Coincident with the evolution of the vertebrate lens an ancestral urochordate type βγ-crystallin gene rapidly expanded and diverged in the ancestral vertebrate before the cyclostomes/gnathostomes split. The β- and γN-crystallin genes were maintained in subsequent evolution, and, given the selection pressure imposed by accurate vision, must be essential for lens function. The γ-crystallin genes show lineage specific expansion and contraction, presumably in adaptation to the demands on vision resulting from (changes in) lifestyle.
Metadata
| Item Type: | Article |
|---|---|
| Additional Information: | Erratum at http://dx.doi.org/10.1007/s00239-010-9387-2 *Sessional lecturer, no ID |
| Keyword(s) / Subject(s): | βγ-Crystallins, Cyclostomes, Urochordata, Cephalochordata, AIM1, lens evolution |
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Research Centres and Institutes: | Structural Molecular Biology, Institute of (ISMB) |
| Depositing User: | Administrator |
| Date Deposited: | 30 Mar 2011 14:10 |
| Last Modified: | 02 Aug 2023 16:54 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/3216 |
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