The Cgl1281-encoding putative transporter of the cation diffusion facilitator family is responsible for alkali-tolerance in <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis> |
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Authors: | Seiki Takeno Mio Nakamura Rie Fukai Junko Ohnishi Masato Ikeda |
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Institution: | (1) Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, Nagano 399-4598, Japan;(2) BioFrontier Laboratories, Kyowa Hakko Kogyo Co., Ltd., Machida, Tokyo 194-8533, Japan |
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Abstract: | Mutants of Corynebacterium glutamicum that were unable to grow under mild alkaline pH conditions were isolated by mutagenesis. Strain AL-43 exhibiting the highest
sensitivity to alkaline pH among the mutants was selected and used to clone a DNA fragment that could complement the phenotype.
Sequencing and subcloning of the cloned 4.0-kb EcoRI DNA fragment showed that the Cgl1281 gene was responsible for the complementation. The deduced amino acid sequence of Cgl1281
was found to show significant sequence similarity with CzcD, a Me2+/H+(K+) antiporter, from Bacillus subtilis and also possess the features of the cation diffusion facilitator (CDF) family: the presence of 6 putative transmembrane
segments and a signature sequence, indicating that the gene product is a member of the CDF family. Chromosomal disruption
of the Cgl1281 rendered C. glutamicum cells sensitive to alkaline pH as well as cobalt, while expression of the gene from a plasmid restored alkali-tolerance to
the wild-type level and also led to increased cobalt resistance. These results demonstrated that the putative transporter
of the CDF family mediates resistance to cobalt and also plays a physiological role in alkaline pH tolerance in C. glutamicum. |
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Keywords: | Alkaline pH tolerance Cation diffusion facilitator family Cobalt resistance Corynebacterium glutamicum |
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