Wn. Jiang et al., THE ROLE OF THE 5'-END UNTRANSLATED REGION OF THE MESSENGER-RNA FOR CSPA, THE MAJOR COLD-SHOCK PROTEIN OF ESCHERICHIA-COLI, IN COLD-SHOCK ADAPTATION, Journal of bacteriology, 178(16), 1996, pp. 4919-4925
During cellular adaptation to low temperature, Escherichia coli transi
ently synthesizes the major cold-shock protein CspA. It was found that
adapation to cold shock is blocked when the 143-base sequence of the
5' untranslated region (5' UTR) of the cspA mRNA is overproduced. The
overproduction of this UTR at 15 degrees C caused the synthesis of not
only CspA but also other cold-shock proteins such as CspB and CsdA to
be no longer transient but rather prolonged, In addition, inhibition
of both the synthesis of cellular proteins other than cold-shock prote
ins and cell growth was observed. Interestingly, when CspA was also ov
erproduced together with the 5' UTR, normal cold-shock adaptive respon
se was resumed without a prolonged lag period of cell growth. This ind
icates that the 5' UTR of the cspA mRNA and its gene product CspA play
a critical role in the regulation of the expression of cold-shock gen
es and cold-shock adaptation. An 11-base common sequence (cold box) wa
s found in the 5' UTRs of cspA, cspB, and csdA mRNAs. Indeed, the 25-b
ase sequence within the 5' UTR of the cspA mRNA containing the cold-bo
x sequence was able to prolong CspA production at 15 degrees C. We pro
pose that a putative repressor binds to the cold-box sequence of the c
old-shock mRNAs during the adaptive process and this binding in turn b
locks the transcription of the cold-shock genes or destablilizes their
mRNAs. CspA appears to promote either directly or indirectly the repr
essor function.