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Mutants of the methylotrophic yeast Pichia pinus defective in C 2 metabolism
Author(s) -
Tolstorukov I. I.,
Efremov B. D.,
Benevolensky S. V.,
Titorenko V. I.,
Sibirny A. A.
Publication year - 1989
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.320050307
Subject(s) - isocitrate lyase , malate synthase , glyoxylate cycle , biology , biochemistry , mutant , alcohol oxidase , catalase , enzyme , ethanol metabolism , yeast , oxidase test , derepression , phosphoenolpyruvate carboxykinase , citrate synthase , lyase , metabolism , malic enzyme , psychological repression , gene , pichia pastoris , gene expression , dehydrogenase , recombinant dna
Abstract A collection of mutants of Pichia pinus which are unable to grow on ethanol but retain the ability to grow on glucose and methanol, was obtained. Genetic and biochemical analysis of these strains revealed mutations in seven nuclear genes affecting activities of isocitrate lyase ( icl1 ), malate synthase ( mls1 ), phosphoenolpyruvate carboxykinase ( pck1 ), ‘malic’ enzyme ( mdd1 ) and acetyl‐CoA synthetase ( acs1 , acs2 and acs3 ). All mutations except acs1 ‐ acs3 have no effect on the activities of other enzymes involved in C 2 metabolism. Mutations acs1 , acs2 and acs3 have a pleiotropic action, leading to partial reduction in activities of isocitrate lyase and malate synthase. Ethanol‐induced repression of the synthesis of the methanol oxidative enzymes, alcohol oxidase and catalase, is not impaired in these seven mutant classes. On the other hand, C 2 compound‐induced inactivation of alcohol oxidase and catalase is impaired in mutants acs1 , acs2 , acs3 and icl1 . It was suggested that glyoxylate and acetate (or acetate precursors) act as low molecular weight effectors, ‘switching on’ inactivation and repression, respectively, of alcohol oxidase and catalase in the medium containing ethanol or acetate.