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J. Bacteriol., Jan 1998, 90-95, Vol 180, No. 1
L Fang, Y Hou and M Inouye
Upon temperature downshift, a group of proteins called cold shock proteins,
such as CspA, CspB, and CsdA, are transiently induced in Escherichia coli.
However, when the 5' untranslated region (5' UTR) of cspA mRNA is
overproduced at low temperature, the expression of cold shock genes is
prolonged or derepressed. It has been proposed that this effect is due to
highly conserved 11-base sequences designated the "cold box" existing in
the 5' UTRs of cspA, cspB, and csdA. Here, we demonstrate that the
overproduction of the 5' UTR of not only cspA but also cspB and csdA mRNAs
causes derepression of all three genes at the same time. Conversely, when
the cold-box region was deleted from the cspA 5' UTR its derepression
function was abolished. The amount of mRNA from the chromosomal cspA gene
was much higher in cells overproducing the wild-type 5' UTR by means of a
plasmid than it was in cells overproducing the cold-box-deleted 5' UTR. The
stability of the chromosomal cspA mRNA in cells overproducing the wild-type
5' UTR was almost identical to that in cells overproducing the
cold-box-deleted 5' UTR. Therefore, the derepression of cspA caused by
overproduction of 5' UTR at the end of the acclimation phase occurs at the
level of transcription but not by mRNA stabilization, indicating that the
cold- box region plays a negative role in cspA transcription in cold shock-
adapted cells. The role of the cold-box region was further confirmed with a
cspA mutant strain containing a cold-box-deleted cspA gene integrated into
the chromosome, which showed a high level of constitutive production of
CspA but not CspB during exponential growth at low temperature.
Copyright © 1998, American Society for Microbiology
Role of the cold-box region in the 5' untranslated region of the cspA mRNA in its transient expression at low temperature in Escherichia coli [In Process Citation]
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
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