Identification of a novel system for boron transport: Atr1 is a main boron exporter in yeast.
Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent protein-tagged Atr1 localized to the cell membrane and vacuole, and ATR1 gene expression was upregulated by boron and several stress conditions. We found that atr1Delta mutants were highly sensitive to boron treatment, whereas cells overexpressing ATR1 were boron resistant. In addition, atr1Delta cells accumulated boron, whereas ATR1-overexpressing cells had low intracellular levels of the element. Furthermore, atr1Delta cells showed stronger boron-dependent phenotypes than mutants deficient in genes previously reported to be implicated in boron metabolism. ATR1 is widely distributed in bacteria, archaea, and lower eukaryotes. Our data suggest that Atr1 functions as a boron efflux pump and is required for boron tolerance.
Department of Molecular Biology and Genetics, Izmir Institute of Technology, 35430 Urla, Izmir, Turkey.
Alaattin
A
Kaya
Huseyin C
HC
Karakaya
Dmitri E
DE
Fomenko
Vadim N
VN
Gladyshev
Ahmet
A
Koc
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001888:Boric Acids / Q000378:metabolism; D001895:Boron / Q000378:metabolism*; D020869:Gene Expression Profiling; D007306:Insecticides / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological
C108080:ATR1 protein, S cerevisiae; D001888:Boric Acids; D007306:Insecticides; D026901:Membrane Transport Proteins; D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; D001895:Boron; C032688:boric acid