JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nakahigashi, K.
Right arrow Articles by Yura, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nakahigashi, K.
Right arrow Articles by Yura, T.

Journal of Bacteriology, September 2001, p. 5302-5310, Vol. 183, No. 18
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.18.5302-5310.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

DnaK Chaperone-Mediated Control of Activity of a sigma 32 Homolog (RpoH) Plays a Major Role in the Heat Shock Response of Agrobacterium tumefaciens

Kenji Nakahigashi,dagger Hideki Yanagi,Dagger and Takashi Yura*

HSP Research Institute, Kyoto Research Park, Kyoto 600-8813, Japan

Received 26 February 2001/Accepted 19 June 2001

RpoH (Escherichia coli sigma 32 and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. Here we studied salient regulatory features of RpoH in Agrobacterium tumefaciens by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37°C. Heat induction of RpoH synthesis occurred at the level of transcription from an RpoH-dependent promoter, coordinately with that of DnaK, and followed by an increase in the RpoH level. Essentially normal induction of heat shock proteins was observed even with a strain that was unable to increase the RpoH level upon heat shock. Moreover, heat-induced accumulation of dnaK mRNA occurred without protein synthesis, showing that preexisting RpoH was sufficient for induction of the heat shock response. These results suggested that controlling the activity, rather than the amount, of RpoH plays a major role in regulation of the heat shock response. In addition, increasing or decreasing the DnaK-DnaJ chaperones specifically reduced or enhanced the RpoH activity, respectively. On the other hand, the RpoH protein was normally stable and remained stable during the induction phase but was destabilized transiently during the adaptation phase. We propose that the DnaK-mediated control of RpoH activity plays a primary role in the induction of heat shock response in A. tumefaciens, in contrast to what has been found in E. coli.

* Corresponding author. Mailing address: 12 Hazama-cho, Shugakuin, Sakyo-ku, Kyoto 606-8071, Japan. Phone and fax: (81) 75-781-7828. E-mail: tayura{at}ip.media.kyoto-u.ac.jp.

dagger Present address: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.

Dagger Present address: Sumitomo Pharmaceutical Co., Niihama 792-0001, Japan.

Journal of Bacteriology, September 2001, p. 5302-5310, Vol. 183, No. 18
0021-9193/01/$04.00+0   DOI: 10.1128/JB.183.18.5302-5310.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 2001 by the American Society for Microbiology. All rights reserved.