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Open Access Research article

Complex evolution of the DAL5 transporter family

Linda Hellborg1*, Megan Woolfit23, Mattias Arthursson-Hellborg4 and Jure Piškur1

Author Affiliations

1 Cell and Organism Biology, Lund University, Lund, Sweden

2 Smurfit Institute of Genetics, Trinity College, University of Dublin, Ireland

3 School of Integrative Biology, University of Queensland, Brisbane, Queensland, 4072, Australia

4 Jayway AB, Malmö, Sweden

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BMC Genomics 2008, 9:164  doi:10.1186/1471-2164-9-164

Published: 11 April 2008

Abstract

Background

Genes continuously duplicate and the duplicated copies remain in the genome or get deleted. The DAL5 subfamily of transmembrane transporter genes has eight known members in S. cerevisiae. All are putative anion:cation symporters of vitamins (such as allantoate, nicotinate, panthotenate and biotin). The DAL5 subfamily is an old and important group since it is represented in both Basidiomycetes ("mushrooms") and Ascomycetes ("yeast"). We studied the complex evolution of this group in species from the kingdom of fungi particularly the Ascomycetes.

Results

We identified numerous gene duplications creating sets of orthologous and paralogous genes. In different lineages the DAL5 subfamily members expanded or contracted and in some lineages a specific member could not be found at all. We also observed a close relationship between the gene YIL166C and its homologs in the Saccharomyces sensu stricto species and two "wine spoiler" yeasts, Dekkera bruxellensis and Candida guilliermondi, which could possibly be the result of horizontal gene transfer between these distantly related species. In the analyses we detect several well defined groups without S. cerevisiae representation suggesting new gene members in this subfamily with perhaps altered specialization or function.

Conclusion

The transmembrane DAL5 subfamily was found to have a very complex evolution in yeast with intra- and interspecific duplications and unusual relationships indicating specialization, specific deletions and maybe even horizontal gene transfer. We believe that this group will be important in future investigations of evolution in fungi and especially the evolution of transmembrane proteins and their specialization.