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Journal of Bacteriology, March 1999, p. 1728-1732, Vol. 181, No. 6
Department of Biological Sciences, University
of Alberta, Edmonton, Alberta, Canada T6G 2E9
Received 14 October 1998/Accepted 13 January 1999
The ability to modify RNA secondary structure is crucial for
numerous cellular processes. We have characterized two RNA helicase genes, crhB and crhC, which are differentially
expressed in the cyanobacterium Anabaena sp.
strain PCC 7120. crhC transcription is limited specifically
to cold shock conditions while crhB is expressed under a
variety of conditions, including enhanced expression in the cold. This
implies that both RNA helicases are involved in the cold acclimation
process in cyanobacteria; however, they presumably perform different
roles in this adaptation. Although both CrhB and CrhC belong to the
DEAD box subfamily of RNA helicases, CrhC encodes a novel RNA helicase,
as the highly conserved SAT motif is modified to FAT. This
alteration may affect CrhC function and its association with specific
RNA targets and/or accessory proteins, interactions required for cold
acclimation. Primer extension and analysis of the 5' untranslated
region of crhC revealed the transcriptional start site, as
well as a number of putative cold shock-responsive elements. The
potential role(s) performed by RNA helicases in the acclimation of
cyanobacteria to cold shock is discussed.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
A Cold Shock-Induced Cyanobacterial RNA
Helicase

*
Corresponding author. Mailing address: Department of
Biological Sciences, University of Alberta, Edmonton, Alberta,
Canada T6G 2E9. Phone: (780) 492-1803. Fax: (780) 492-9234. E-mail:
g.owttrim{at}ualberta.ca.
Present address: Department of Forensic Sciences, The George
Washington University, Washington, D.C.
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