This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Amo, T. Articles by Imanaka, T. Search for Related Content PubMed PubMed Citation Articles by Amo, T. Articles by Imanaka, T.

 Previous Article  |  Next Article 

Journal of Bacteriology, November 2003, p. 6340-6347, Vol. 185, No. 21
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.21.6340-6347.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Biochemical Properties and Regulated Gene Expression of the Superoxide Dismutase from the Facultatively Aerobic Hyperthermophile Pyrobaculum calidifontis

Taku Amo, Haruyuki Atomi, and Tadayuki Imanaka^*

Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan

Received 12 May 2003/ Accepted 15 August 2003

Superoxide dismutase (SOD) was purified from a facultatively aerobic hyperthermophilic archaeon, Pyrobaculum calidifontis VA1. The purified native protein from aerobically grown cells exhibited 1,960 U of SOD activity/mg and contained 0.86 ± 0.04 manganese and <0.01 iron atoms per subunit. The gene encoding SOD was cloned and expressed in Escherichia coli. Although the recombinant protein was soluble, little activity was observed due to the lack of metal incorporation. Reconstitution of the enzyme by heat treatment with either Mn or Fe yielded a highly active protein with specific activities of 1,970 and 434 U/mg, respectively. This indicated that the SOD from P. calidifontis was a cambialistic SOD with a preference toward Mn in terms of activity. Interestingly, reconstitution experiments in vitro indicated a higher tendency of the enzyme to incorporate Fe than Mn. When P. calidifontis was grown under anaerobic conditions, a majority of the native SOD was incorporated with Fe, indicating the cambialistic property of this enzyme in vivo. We further examined the expression levels of SOD and a previously characterized Mn catalase from this strain in the presence or absence of oxygen. Northern blot, Western blot, and activity measurement analyses revealed that both genes are expressed at much higher levels under aerobic conditions. We also detected a rapid response in the biosynthesis of these enzymes once the cells were exposed to oxygen.

---

* Corresponding author. Mailing address: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. Phone: 81(0)75-383-2777. Fax: 81(0)75-383-2778. E-mail: imanaka{at}sbchem.kyoto-u.ac.jp.

---

Journal of Bacteriology, November 2003, p. 6340-6347, Vol. 185, No. 21
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.21.6340-6347.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Cozen, A. E., Weirauch, M. T., Pollard, K. S., Bernick, D. L., Stuart, J. M., Lowe, T. M. (2009). Transcriptional Map of Respiratory Versatility in the Hyperthermophilic Crenarchaeon Pyrobaculum aerophilum. J. Bacteriol. 191: 782-794 [Abstract] [Full Text]  
• Guo, F.-x., E, S.-j., Liu, S.-a., Chen, J., Li, D.-c. (2008). Purification and characterization of a thermostable MnSOD from the thermophilic fungus Chaetomium thermophilum. Mycologia 100: 375-380 [Abstract] [Full Text]