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Applied and Environmental Microbiology, December 2008, p. 7306-7312, Vol. 74, No. 23
0099-2240/08/$08.00+0 doi:10.1128/AEM.01245-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Expression Profiles and Physiological Roles of Two Types of Molecular Chaperonins from the Hyperthermophilic Archaeon Thermococcus kodakarensis
,
Shinsuke Fujiwara,1,2*
Ryohei Aki,2
Masaya Yoshida,2
Hiroki Higashibata,2
Tadayuki Imanaka,3 and
Wakao Fukuda2
Department of Bioscience, School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan,1 Nanobiotechnology Research Center, Graduate School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan,2 Department of Biotechnology, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan3
Received 5 June 2008/ Accepted 29 September 2008
Thermococcus kodakarensis possesses two chaperonins, CpkA and CpkB, and their expression is induced by the downshift and upshift, respectively, of the cell cultivation temperature. The expression levels of the chaperonins were examined by using specific antibodies at various cell growth temperatures in the logarithmic and stationary phases. At 60°C, CpkA was highly expressed in both the logarithmic and stationary phases; however, CpkB was not expressed in either phase. At 85°C, CpkA and CpkB were expressed in both phases; however, the CpkA level was decreased in the stationary phase. At 93°C, CpkA was expressed only in the logarithmic phase and not in the stationary phase. In contrast, CpkB was highly expressed in both phases. The results of reverse transcription-PCR experiments showed the same growth phase- and temperature-dependent profiles as observed in immunoblot analyses, indicating that the expression of cpkA and cpkB is regulated at the mRNA level. The cpkA or cpkB gene disruptant was then constructed, and its growth profile was monitored. The cpkA disruptant showed poor cell growth at 60°C but no significant defects at 85°C and 93°C. On the other hand, cpkB disruption led to growth defects at 93°C but no significant defects at 60°C and 85°C. These data indicate that CpkA and CpkB are necessary for cell growth at lower and higher temperatures, respectively. The logarithmic-phase-dependent expression of CpkA at 93°C suggested that CpkA participates in initial cell growth in addition to lower-temperature adaptation. Promoter mapping and quantitative analyses using the Phr (Pyrococcus heat-shock regulator) gene disruptant revealed that temperature-dependent expression was achieved in a Phr-independent manner.
* Corresponding author. Mailing address: Department of Bioscience, School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan. Phone: 81-79-565-7829. Fax: 81-79-565-9077. E-mail: fujiwara-s{at}kwansei.ac.jp
Published ahead of print on 3 October 2008.
Supplemental material for this article may be found at http://aem.asm.org/.
Applied and Environmental Microbiology, December 2008, p. 7306-7312, Vol. 74, No. 23
0099-2240/08/$08.00+0 doi:10.1128/AEM.01245-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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