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Journal of Bacteriology, July 2001, p. 3848-3854, Vol. 183, No. 13
UPR9073 du CNRS, Institut de Biologie
PhysicoChimique, 75005 Paris, France
Received 13 February 2001/Accepted 12 April 2001
Polynucleotide phosphorylase (PNPase) synthesis is translationally
autocontrolled via an RNase III-dependent mechanism, which results in a
tight correlation between protein level and messenger stability. In
cells grown at 18°C, the amount of PNPase is twice that found in
cells grown at 30°C. To investigate whether this effect was
transcriptional or posttranscriptional, the expression of a set of
pnp-lacZ transcriptional and translational fusions was
analyzed in cells grown at different temperatures. In the absence of
PNPase, there was no increase in pnp-lacZ expression, indicating that the increase in pnp expression occurs at
a posttranscriptional level. Other experiments clearly show that
increased pnp expression at low temperature is only
observed under conditions in which the autocontrol mechanism of PNPase
is functional. At low temperature, the destabilizing effect of PNPase
on its own mRNA is less efficient, leading to a decrease in repression
and an increase in the expression level.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.13.3848-3854.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Increased Expression of Escherichia coli
Polynucleotide Phosphorylase at Low Temperatures Is Linked to a
Decrease in the Efficiency of Autocontrol
and
*
Corresponding author. Mailing address: UPR9073 du CNRS,
Institut de Biologie PhysicoChimique, 13 rue Pierre et Marie Curie, 75005 Paris, France. Phone: 33 (0)1 58 41 51 27. Fax: 33 (0)1 58 41 50 20. E-mail: portier{at}ibpc.fr.
Present address: Laboratory of Vectorology and Gene
Transfer, U.M.R 1582 (CNRS-Rhone Poulenc Gencell) Institut
Gustave Roussy, 94805 Villejuif, France.
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