title: The putative transcriptional activator MSN1 promotes chromium accumulation in Saccharomyces cerevisiae.
abstract: Yeast is a good system for studying molecular mechanisms of metal tolerance. Using a mini-Tn mutagenized yeast pool, we isolated a chromate-tolerant mutant, CrT9, that displayed metal-specific tolerance since it was only tolerant to Cr(VI), not to Cr(III), Cd, As, or Fe. The Cr-tolerance of CrT9 appeared to be due to reduced Cr accumulation as it accumulated only 56% as much as WT (Y800). Using IPCR (inverse PCR), we found that the mini-Tn had been inserted at nt 741 of the transcriptional activator, MSN1. MSN1 is a multifunctional protein involved in invertase activity, iron uptake, starch degradation, pseudohyphal growth, and osmotic gene expression. We found that there was only one mini-Tn insertion in CrT9 since MSN1 and mini-Tn probes hybridized to the same DNA fragment, and the MSN1 probe detected an enlarged MSN1 mRNA. When we over-expressed MSN1 in CrT9 and WT, both accumulated larger amounts of Cr. We conclude that Cr accumulation in S. cerevisiae is promoted by the transcriptional activator MSN1.
authors.affiliation: Department of Molecular Biology, Sejong University, Seoul 143-747, Korea.
authors.forename: Kwang Suk
authors.initials: KS
authors.lastname: Chang
authors.forename: Jong Im
authors.initials: JI
authors.lastname: Won
authors.forename: Mi Ran
authors.initials: MR
authors.lastname: Lee
authors.forename: Chang Eun
authors.initials: CE
authors.lastname: Lee
authors.forename: Kyongmin Hwang
authors.initials: KH
authors.lastname: Kim
authors.forename: Ky Young
authors.initials: KY
authors.lastname: Park
authors.forename: Seong-Ki
authors.initials: SK
authors.lastname: Kim
authors.forename: June Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Seongbin
authors.initials: S
authors.lastname: Hwang
mesh_terms: D002857:Chromium / Q000378:metabolism*; D004251:DNA Transposable Elements / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D017874:Immediate-Early Proteins; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; C490188:MSN1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D002857:Chromium