Regulation of monovalent ion homeostasis and pH by the Ser-Thr protein phosphatase SIT4 in Saccharomyces cerevisiae.
J Biol Chem
; 275(40): 30957-61, 2000 Oct 06.
Article
em En
| MEDLINE
| ID: mdl-10921924
A gene, SIT4, was identified as corresponding to a serine/threonine protein phosphatase and when overexpressed confers lithium tolerance in galactose medium to the budding yeast Saccharomyces cerevisiae. This gene has been previously identified as a regulator of the cell cycle and involved in nitrogen sensing. It is shown that the transcription levels of SIT4 are induced by low concentrations of Li(+) in a time-dependent manner. Na(+) and K(+) at high concentrations, but not sorbitol, also induce transcription. As a response to Na(+) or Li(+) stress, yeast cells lower the intracellular K(+) content. This effect is enhanced in cells overexpressing SIT4, which also increase (86)Rb efflux after the addition of Na(+) or Li(+) to the extracellular medium. Another feature of SIT4-overexpressing cells is that they maintain a more alkaline pH of 6.64 compared with 6.17 in the wild type cells. It has been proposed that the main pathway of salt tolerance in yeast is mediated by a P-type ATPase, encoded by PMR2A/ENA1. However, our results show that in a sit4 strain, expression of ENA1 is still induced by monovalent cations, and overexpression of SIT4 does not alter the amount of ENA1 transcript. These results show that SIT4 acts in a parallel pathway not involving induction of transcription of ENA1 and suggest a novel function for SIT4 in response to salt stress.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
Fosfoproteínas Fosfatases
/
Proteínas de Transporte de Cátions
/
Proteínas de Saccharomyces cerevisiae
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Estados Unidos