Affiliation:
1. Department of Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas, P.O. Box 73, E-46100 Burjassot, Valencia, Spain
Abstract
ABSTRACT
Recently, the academic interest in the yeast
Torulaspora delbrueckii
has increased notably due to its high resistance to several types of stress, including salt and osmotic imbalance. However, the molecular mechanisms underlying these unusual properties are poorly understood. In
Saccharomyces cerevisiae
, the high-salt response is mediated by calcineurin, a conserved Ca
2+
/calmodulin-modulated protein phosphatase that regulates the transcriptional factor Crz1p. Here, we cloned the
T. delbrueckii
Td
CRZ1
gene, which encodes a putative zinc finger transcription factor homologue to Crz1p. Consistent with this, overexpression of Td
CRZ1
enhanced the salt tolerance of
S. cerevisiae
wild-type cells and suppressed the sensitivity phenotype of
cnb1
Δ and
crz1
Δ mutants to monovalent and divalent cations. However,
T. delbrueckii
cells lacking TdCrz1p showed phenotypes distinct from those previously observed in
S. cerevisiae crz1
Δ mutants. Quite remarkably, Td
crz1
-null cells were insensitive to high Na
+
and were more Li
+
tolerant than wild-type cells. Clearly, TdCrz1p was not required for the salt-induced transcriptional activation of the Td
ENA1
gene, encoding a putative P-type ATPase homologue to the main
S. cerevisiae
Na
+
pump
ENA1
. Furthermore,
T. delbrueckii
cells were insensitive to the immunosuppressive agents FK506 and cyclosporine A, both in the presence and in the absence of NaCl. Signaling through the calcineurin/Crz1 pathway appeared to be essential only on high-Ca
2+
/Mn
2+
media. Hence,
T. delbrueckii
and
S. cerevisiae
differ in the regulatory circuits and mechanisms that drive the adaptive response to salt stress.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology
Cited by
30 articles.
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