The putative transcriptional activator MSN1 promotes chromium accumulation in Saccharomyces cerevisiae.
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.
Chang
Kwang Suk
KS
Department of Molecular Biology, Sejong University, Seoul 143-747, Korea.
Won
Jong Im
JI
Lee
Mi Ran
MR
Lee
Chang Eun
CE
Kim
Kyongmin Hwang
KH
Park
Ky Young
KY
Kim
Seong-Ki
SK
Lee
June Seung
JS
Hwang
Seongbin
S
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*
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