GENETICS OF YEAST HEXOKINASE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 86  (4) , 727-744
Abstract
Two independent isolates of Saccharomyces cerevisiae lacking hexokinase activity (EC 2.7.1.1) are described. Both mutant strains grow on glucose but are unable to grow on fructose, and contain 2 mutant genes hxk1 and hxk2 each. The mutations are recessive and noncomplementing. Genetic analysis suggests that these 2 unlinked genes hxk1 and hxk2 determine, independently of each other, the synthesis of hexokinase isozymes P1 and P2, respectively. The mutant gene hxk1 is located on chromosome V1R distal to met10, and hxk2 is on chromosome IIIR distal to MAL2. Of 4 hexokinase-positive spontaneous reversion, 1 is very tightly linked to hxk1 and the other 3 to the hxk2 locus. The reverted enzymes are considerably more thermolabile than the respective wild-type enzymes, and in one case show altered immunological properties. Data are presented which suggest that the hxk1 and hxk2 mutations are missense mutations in the sturctural genes of hexokinase P1 and hexokinase P2, respectively. These are presumably the only enzymes that allow S. cerevisiae to grow on fructose.

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