Saccharomyces cerevisiae Bor1p is a boron exporter and a key determinant of boron tolerance.
Boron is toxic to living organisms when present in excess. Saccharomyces cerevisiae Bor1p is a plasma membrane protein that decreases the intracellular concentration of boron and confers boron tolerance in yeasts. We investigated the detailed characteristics of boron transport by Bor1p and its roles in boron tolerance. Boron transport assays showed that the bor1 deletion mutant (bor1Delta) accumulates higher intracellular concentrations of boron and has a lower rate of boron export. The bor1Delta showed greater susceptibility to high concentrations of boron than the wild-type strain, and the growth rates of both strains were negatively correlated with the intracellular concentrations of boron. With normal to toxic levels of external boron, green fluorescent protein (GFP)-tagged Bor1p localized to the plasma membrane irrespective of the concentration of boron in the medium. Taken together, these results establish Bor1p as a plasma membrane boron exporter and a key determinant of boron tolerance.
Takano
Junpei
J
Biotechnology Research Center, University of Tokyo, Yayoi, Tokyo, Japan. ujtakano@mail.ecc.u-tokyo.ac.jp
Kobayashi
Masaharu
M
Noda
Yoichi
Y
Fujiwara
Toru
T
D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000502:physiology*; D001692:Biological Transport; D001895:Boron / Q000378:metabolism* / Q000633:toxicity; D002462:Cell Membrane / Q000378:metabolism; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000032:analysis; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*
D001457:Anion Exchange Protein 1, Erythrocyte; C511808:Bor1 protein, S cerevisiae; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D001895:Boron