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Applied and Environmental Microbiology, October 2007, p. 5990-6000, Vol. 73, No. 19
0099-2240/07/$08.00+0 doi:10.1128/AEM.00863-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
,
Min Jeong Sohn,1,2,
Doo-Byoung Oh,1
Ohsuk Kwon,1
Sang Ki Rhee,1
Cheol-Goo Hur,1
Sang Yup Lee,2
Gerd Gellissen,1,
and
Hyun Ah Kang1*
Omics and Integration Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoeun-dong, Yuseong-gu, Daejeon 305-806, Korea,1 Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea2
Received 17 April 2007/ Accepted 23 July 2007
The genomewide gene expression profiling of the methylotrophic yeast Hansenula polymorpha exposed to cadmium (Cd) allowed us to identify novel genes responsive to Cd treatment. To select genes whose promoters can be useful for construction of a cellular Cd biosensor, we further analyzed a set of H. polymorpha genes that exhibited >6-fold induction upon treatment with 300 µM Cd for 2 h. The putative promoters, about 1,000-bp upstream fragments, of these genes were fused with the yeast-enhanced green fluorescence protein (GFP) gene. The resultant reporter cassettes were introduced into H. polymorpha to evaluate promoter strength and specificity. The promoter derived from the H. polymorpha SEO1 gene (HpSEO1) was shown to drive most strongly the expression of GFP upon Cd treatment among the tested promoters. The Cd-inducible activity was retained in the 500-bp deletion fragment of the HpSEO1 promoter but was abolished in the further truncated 250-bp fragment. The 500-bp HpSEO1 promoter directed specific expression of GFP upon exposure to Cd in a dose-dependent manner, with Cd detection ranging from 1 to 900 µM. Comparative analysis of the Saccharomyces cerevisiae SEO1 (ScSEO1) promoter revealed that the ScSEO1 promoter has a broader specificity for heavy metals and is responsive to arsenic and mercury in addition to Cd. Our data demonstrate the potential use of the HpSEO1 promoter as a bioelement in whole-cell biosensors to monitor heavy metal contamination, particularly Cd.
Published ahead of print on 27 July 2007.
Supplemental material for this article may be found at http://aem.asm.org/.
J.-N.P. and M.J.S. contributed equally to this study.
Present address: PharmedArtis GmbH, Forckenbeckstr. 6, 52074 Aachen, Germany.
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