Complex evolution of the DAL5 transporter family

Linda Hellborg,Mattias Arthursson-Hellborg,Megan Woolfit,Jure Piškur

doi:10.1186/1471-2164-9-164

Linda Hellborg, Mattias Arthursson-Hellborg + Show 2 more

Open Access

https://doi.org/10.1186/1471-2164-9-164

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Abstract

BackgroundGenes 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.ResultsWe 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.ConclusionThe 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.

Highlights

Genes continuously duplicate and the duplicated copies remain in the genome or get deleted
The allantoate permease transporters are known to be an ancient subfamily [11], and as expected we found almost all members of the DAL5 group represented in the Hemiascomycete, Euascomycete and Basidiomycete taxa included in our analysis
Crucial genes often show an interesting evolution and transmembrane proteins are often essential for the survival of the yeast cells

Summary

Introduction

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. Transmembrane transporters of unicellular organisms, like yeast, are one of the primary links between the outer world and the metabolic pathways inside the cell. The importance of these genes is seen in the substantial proportion of transporter genes within the yeast genome (10%) [1]. Expansion or contraction of gene numbers in various transporter subfamilies can indicate metabolic abilities: for example, peroxisomal and long chain fatty acid transporters have undergone amplification in Y. lipolytica, which is known to grow on fatty acids [8]. Genes belonging to two heavy metal transporter subfamilies, SIT and CT2, have been amplified 14 and 10 times respectively in Y. lipolytica [9], possibly as the result of a natural symbiosis with bacteria providing ironsiderophores and/or other natural chelators

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