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Isolation and characterization of Kluyveromyces marxianus mutants deficient in malate transport
Author(s) -
Queirós O.,
Casal M.,
Althoff S.,
MoradasFerreira P.,
Leão C.
Publication year - 1998
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/(sici)1097-0061(19980330)14:5<401::aid-yea234>3.0.co;2-t
Subject(s) - malic enzyme , biochemistry , malate dehydrogenase , malic acid , biology , mutant , phosphoenolpyruvate carboxylase , catabolite repression , glyoxylate cycle , enzyme , dehydrogenase , gene , citric acid
In malic acid‐grown cells of the strains ATCC 10022 and KMS3 of Kluyveromyces marxianus the transport of malic acid occurred by a malate‐proton symport, which accepted l‐malic, d‐malic, succinic and fumaric acids, but not tartaric, malonic or maleic acids. The system was inducible and subjected to glucose repression. Mutants of the strain KMS3, unable to grow in a medium with malic acid, were isolated and checked for their capacity to utilize several carbon sources and to transport dicarboxylic acids by the malate‐proton symport. Two distinct clones affected on malate transport were obtained. Both were able to grow on a medium with glycerol or ethanol but not with dl‐malic, succinic, oxoglutaric and oxaloacetic acids as the sole carbon and energy sources. However, while one of the mutants (Mal7) displayed activity levels for the enzymes malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase similar to those of the wild strain, in the other mutant type (Mal6) the activities for the same enzymes were significantly reduced. Plasma membranes from derepressed cells of the wild strain and of the mutants Mal6 and Mal7 were isolated and the protein analysed by SDS–PAGE. The electrophoretic patterns of these preparations differed in a polypeptide with an apparent molecular mass of about 28 kDa, which was absent only in the mutant Mal7. The results indicated that Mal7 can be affected in a gene that encodes a malate carrier in K. marxianus . © 1998 John Wiley & Sons, Ltd.