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 arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Awano, N.
Right arrow Articles by Phadtare, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Awano, N.
Right arrow Articles by Phadtare, S.

 Previous Article  |  Next Article 

Journal of Bacteriology, September 2008, p. 5924-5933, Vol. 190, No. 17
0021-9193/08/$08.00+0     doi:10.1128/JB.00500-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

RNase Activity of Polynucleotide Phosphorylase Is Critical at Low Temperature in Escherichia coli and Is Complemented by RNase II{triangledown}

Naoki Awano, Masayori Inouye, and Sangita Phadtare*

Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Received 11 April 2008/ Accepted 27 June 2008

In Escherichia coli, the cold shock response is exerted upon a temperature change from 37°C to 15°C and is characterized by induction of several cold shock proteins, including polynucleotide phosphorylase (PNPase), during acclimation phase. In E. coli, PNPase is essential for growth at low temperatures; however, its exact role in this essential function has not been fully elucidated. PNPase is a 3'-to-5' exoribonuclease and promotes the processive degradation of RNA. Our screening of an E. coli genomic library for an in vivo counterpart of PNPase that can compensate for its absence at low temperature revealed only one protein, another 3'-to-5' exonuclease, RNase II. Here we show that the RNase PH domains 1 and 2 of PNPase are important for its cold shock function, suggesting that the RNase activity of PNPase is critical for its essential function at low temperature. We also show that its polymerization activity is dispensable in its cold shock function. Interestingly, the third 3'-to-5' processing exoribonuclease, RNase R of E. coli, which is cold inducible, cannot complement the cold shock function of PNPase. We further show that this difference is due to the different targets of these enzymes and stabilization of some of the PNPase-sensitive mRNAs, like fis, in the {Delta}pnp cells has consequences, such as accumulation of ribosomal subunits in the {Delta}pnp cells, which may play a role in the cold sensitivity of this strain.

* Corresponding author. Mailing address: Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854. Phone: (732) 235-4116. Fax: (732) 235-4559. E-mail: phadtasa{at}umdnj.edu

{triangledown} Published ahead of print on 7 July 2008.

Journal of Bacteriology, September 2008, p. 5924-5933, Vol. 190, No. 17
0021-9193/08/$08.00+0     doi:10.1128/JB.00500-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»