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J Bacteriol, April 1998, p. 2014-2020, Vol. 180, No. 8
Department of Microbiology, College of
Natural Sciences, and Research Center for Molecular Microbiology,
Seoul National University, Seoul 151-742, Korea
Received 3 September 1997/Accepted 3 February 1998
Streptomyces coelicolor Müller contains two
superoxide dismutases (SODs), nickel-containing (NiSOD) and iron- and
zinc-containing SOD (FeZnSOD). The sodF gene encoding
FeZnSOD was isolated by using PCR primers corresponding to the
N-terminal peptide sequence of the purified FeZnSOD and a C-terminal
region conserved among known FeSODs and MnSODs. The deduced amino acid
sequence exhibited highest similarity to Mn- and FeSODs from
Propionibacterium shermanii and Mycobacterium
spp. The transcription start site of the sodF gene was
determined by primer extension. When the sodF gene was cloned in pIJ702 and introduced into Streptomyces lividans
TK24, it produced at least 30 times more FeZnSOD than the control
cells. We disrupted the sodF gene in S. lividans TK24 and found that the disruptant did not produce any
FeZnSOD enzyme activity but produced more NiSOD. The expression of the
cloned sodF gene in TK24 cells was repressed significantly
by Ni, consistent with the regulation pattern in nonoverproducing
cells. This finding suggests that the cloned sodF gene
contains the cis-acting elements necessary for Ni
regulation. When the sodF mRNA in S. coelicolor Müller cells was analyzed by S1 mapping of both 5' and 3' ends, we found that Ni caused a reduction in the level of monocistronic sodF transcripts. Ni did not affect the stability of
sodF mRNA, indicating that it regulates transcription.
S. lividans TK24 cells overproducing FeZnSOD became more
resistant to oxidants such as menadione and lawsone than the control
cells, suggesting the protective role of FeZnSOD. However, the
sodF disruptant survived as well as the wild-type strain in
the presence of these oxidants, suggesting the complementing role of
NiSOD increased in the disruptant.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Expression and Regulation of the sodF
Gene Encoding Iron- and Zinc-Containing Superoxide Dismutase in
Streptomyces coelicolor Müller
*
Corresponding author. Mailing address: Department of
Microbiology, College of Natural Sciences, and Research Center
for Molecular Microbiology, Seoul National University,
Seoul 151-742, Korea. Phone: 82-2-880-6706. Fax: 82-2-888-4911. E-mail: jhroe{at}plaza.snu.ac.kr.
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