Reduction of aluminum toxicity by 2-isopropylmalic acid in the budding yeast Saccharomyces cerevisiae.
The budding yeast Saccharomyces cerevisiae secretes 2-isopropylmalic acid (2-iPMA), an intermediate in leucine biosynthesis. Because 2-iPMA binds Al(III) in the culture medium, it is thought to reduce toxicity by Al(III). The effects of 2-iPMA and malic acid (MA) on Al toxicity were investigated in a medium with a low pH and low concentrations of phosphates and magnesium. The reduction in the growth of S. cerevisiae observed in the presence of 100 muM Al(III) ions was relieved more by the addition of 1.0 mM 2-iPMA than by 1.0 mM MA, indicating that 2-iPMA possesses superior Al(III)-ion detoxification ability. Investigations using the wild type and the deltaleu4 and deltaleu9 mutant strains indicated that secretion of a sufficient level of 2-iPMA was required to enhance the Al tolerance. It is thought that 2-iPMA secreted from the yeast cells chelates Al ions and prevents them from entering the cells, resulting in Al tolerance.
Suzuki
Taisuke
T
Department of Applied Biological Chemistry, School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-5687, Japan.
Tamura
Shun
S
Nakanishi
Hiromi
H
Tashiro
Mitsuru
M
Nishizawa
Naoko K
NK
Yoshimura
Etsuro
E
D015079:2-Isopropylmalate Synthase / Q000235:genetics; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000633:toxicity*; D002712:Chlorides / Q000633:toxicity*; D008293:Malates / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
C502920:2-isopropylmalic acid; D017607:Aluminum Compounds; D002712:Chlorides; D008293:Malates; D029701:Saccharomyces cerevisiae Proteins; D000077410:Aluminum Chloride; C030298:malic acid; D015079:2-Isopropylmalate Synthase; C080062:LEU4 protein, S cerevisiae