ISSN:
1432-072X
Keywords:
Pichia guilliermondii
;
Chorismate mutase
;
Tryptophan auxotrophy
;
Regulatory mutant
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract We have isolated the tryptophan auxotrophic mutant strain, PK101, of Pichia guilliermondii. This strain is not defective in any of the tryptophan biosynthetic enzymes, but its chrismate mutase, an enzyme of the phenylalanine-tyrosine biosynthesis, is changed. In comparison with the wild type chorismate mutase, the enzyme of PK101 is characterized by a complete loss of sensitivity to l-phenylalanine inhibition and to a considerable loss of sensitivity to l-tryptophan activation. Furthermore, the chorismate mutase activity of the mutant is more than 7-fold higher in the absence of l-tryptophan than in the wild type. The PK101 enzyme is also changed in the pH optimum and in some kinetic constants. We found an increased intracellular pool of both phenylalanine and tyrosine and a reduced contents of tryptophan in the mutant cells. Our genetic data indicate that the mutant phenotype is dominant over the wild type.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00414425
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