HOL1 mutations confer novel ion transport in Saccharomyces cerevisiae.
Saccharomyces cerevisiae histidine auxotrophs are unable to use L-histidinol as a source of histidine even when they have a functional histidinol dehydrogenase. Mutations in the hol1 gene permit growth of His- cells on histidinol by enhancing the ability of cells to take up histidinol from the medium. Second-site mutations linked to HOL1-1 further increase histidinol uptake. HOL1 double mutants and, to a lesser extent, HOL1-1 single mutants show hypersensitivity to specific cations added to the growth medium, including Na+, Li+, Cs+, Be2+, guanidinium ion, and histidinol, but not K+, Rb+, Ca2+, or Mg2+. The Na(+)-hypersensitive phenotype is correlated with increased uptake and accumulation of this ion. The HOL1-1-101 gene was cloned and used to generate a viable haploid strain containing a hol1 deletion mutation (hol1 delta). The uptake of cations, the dominance of the mutant alleles, and the relative inability of hol1 delta cells to take up histidinol or Na+ suggest that hol1 encodes an ion transporter. The novel pattern of ion transport conferred by HOL1-1 and HOL1-1-101 mutants may be explained by reduced selectivity for the permeant ions.
Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208.
R F
RF
Gaber
M C
MC
Kielland-Brandt
G R
GR
Fink
D000429:Alcohol Oxidoreductases / Q000235:genetics*; D002872:Chromosome Deletion; D003001:Cloning, Molecular / Q000379:methods; D004271:DNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D005799:Genes, Dominant; D005800:Genes, Fungal; D005838:Genotype; D006579:Heterozygote; D006639:Histidine / Q000378:metabolism; D006641:Histidinol / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
D004271:DNA, Fungal; D006639:Histidine; D006641:Histidinol; D012964:Sodium; D000429:Alcohol Oxidoreductases; C021358:histidinol dehydrogenase