ISSN:
1432-0983
Keywords:
Schwanniomyces occidentalis
;
Yeast
;
Hexokinase
;
Glucokinase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Hexose-phosphorylating enzymes from the starch-utilizing yeast Schwanniomyces occidentalis were purified and two isoenzymes separated. The substrate pattern characterized one of these as a hexokinase phosphorylating glucose and fructose and the other as a glucokinase unable to phosphorylate fructose. The purified Schw. occidentalis hexokinase had a KM value of 0.98 mM for glucose and 9.3 mM for fructose. The hexokinase gene was cloned by cross hybridization with a probe from the Saccharomyces cerevisiae HXK2 gene. Deletion of Schw. occidentalis hexokinase by gene replacement yielded a mutant unable to grow on fructose as sole carbon source, but still growing on glucose. Deletion mutants of Schw. occidentalis hexokinase prevented glucose repression of invertase and maltase. Growth deficiences and the defect of glucose repression of a S. cerevisiae hexokinase null mutant could be restored by heterologous expression of the Schw. occidentalis hexokinase. Moreover, the results clearly showed the existence of a separate glucokinase in Schw. occidentalis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00352102
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