Association of glutathione synthetase deficiency and diminished amino acid transport in yeast

On the role of glutathione in the transport of amino acid in the yeast Saccharomyces cerevisiae: contradictory results

“…Moreover, we observed (table 1) that various mutations, affecting amino acid permeation systems, were not linked to any deficiency in the glutathione biosynthesis ability of Saccharomyces eerevisiae. These observations are inconsistent with the report [7] that the gap-mutant, a strain impaired in the general amino acid permease [ 16], has a strongly reduced glutathione pool, consequent to a deficiency in glutathione synthetase. In [7] the effect seemed to be linked to the growth phase of the yeast, a view not shared by us after a detailed analysis of glutathione pool in relation to the growth phase of the microorganism ( fig.2).…”

“…These observations are inconsistent with the report [7] that the gap-mutant, a strain impaired in the general amino acid permease [ 16], has a strongly reduced glutathione pool, consequent to a deficiency in glutathione synthetase. In [7] the effect seemed to be linked to the growth phase of the yeast, a view not shared by us after a detailed analysis of glutathione pool in relation to the growth phase of the microorganism ( fig.2). However, in [7] obstacles in the estimation of glutathione synthetase by the standard method [10] were not encountered.…”

“…In a preliminary study of 7-glutamyltranspeptidase (EC 2.3.2.2) in several mutant strains of yeast, defective in amino acid transport, we reported that the problem was of considerable complexity and that a role of glutathione in the amino acid transport cannot be delineated [8]. Here we show that to the contrary of [7] no linkage between glutathione and amino acid transport can be demonstrated in Saceharomyces cerevisiae.…”

“…In [7] the effect seemed to be linked to the growth phase of the yeast, a view not shared by us after a detailed analysis of glutathione pool in relation to the growth phase of the microorganism ( fig.2). However, in [7] obstacles in the estimation of glutathione synthetase by the standard method [10] were not encountered. This is puzzling due to the high intracellular level of 7-glutamyltranspeptidase when growing the wild-type strain and the gap-mutant on proline [8].…”

“…In [7] the phenotype of a mutant strain of Saccharomyces cerevisiae, impaired in the general amino acid permease, was related to a depletion in the glutathione pool, resulting from a deficiency in glutathione synthetase (EC 6.3.2.3). In a preliminary study of 7-glutamyltranspeptidase (EC 2.3.2.2) in several mutant strains of yeast, defective in amino acid transport, we reported that the problem was of considerable complexity and that a role of glutathione in the amino acid transport cannot be delineated [8].…”