Multiple cis-regulatory elements and the yeast sulphur regulatory network are required for the regulation of the yeast glutathione transporter, Hgt1p.

Srikanth, Chittur V and Vats, Purva and Bourbouloux, Andrée and Delrot, Serge and Bachhawat, Anand K (2005) Multiple cis-regulatory elements and the yeast sulphur regulatory network are required for the regulation of the yeast glutathione transporter, Hgt1p. Current genetics, 47 (6). pp. 345-58. ISSN 0172-8083

PDF bachhawat2005.pdf - Published Version Restricted to Registered users only Download (406Kb) | Request a copy

Abstract

HGT1 encodes a high-affinity glutathione transporter in the yeast Saccharomyces cerevisiae that is induced under sulphur limitation. The present work demonstrates that repression by organic sulphur sources is under the control of the classic sulphur regulatory network, as seen by the absence of expression in a met4delta background. Cysteine appeared to be the principal regulatory molecule, since elevated levels were seen in str4delta strains (deficient in cysteine biosynthesis) that could be repressed by elevated levels of cysteine, but not by methionine or glutathione. Investigations into cis-regulatory elements revealed that the previously described motif, a 9-bp cis element, CCGCCACAC, located at the -356 to -364 region of the promoter could in fact be refined to a 7-bp CGCCACA motif that is also repeated at -333 to -340. The second copy of this motif was essential for activity, since mutations in the core region of the second copy completely abolished activity and regulation by sulphur sources. Activity, but not regulation, could be restored by reintroducing an additional copy upstream of the first copy. A third region, GCCGTCTGCAAGGCA, conserved in the HGT1 promoters of the different Saccharomyces spp, was observed at -300 to -285 but, while mutations in this region did not lead to any loss in repression, the basal and induced levels were significantly increased. In contrast to a previous report, no evidence was found for regulation by the VDE endonuclease. The strong repression at the transport level by glutathione seen in strains overexpressing HGT1 was due to a glutathione-dependent toxicity in these cells.

Item Type:	Article
Additional Information:	Copyright of this article belongs to Springer Science.
Subjects:	Q Science > QH Natural history > QH426 Genetics
Depositing User:	Dr. K.P.S.Sengar
Date Deposited:	08 Jan 2012 05:41
Last Modified:	08 Jan 2012 05:41
URI:	http://crdd.osdd.net/open/id/eprint/180

Actions (login required)

View Item