The role of the 5'-end untranslated region of the mRNA for CspA, the major cold-shock protein of Escherichia coli, in cold-shock adaptation.
During cellular adaptation to low temperature, Escherichia coli transiently synthesizes the major cold-shock protein CspA. It was found that adaptation 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 proteins and cell growth was observed. Interestingly, when CspA was also overproduced together with the 5' UTR, normal cold-shock adaptive response was resumed without a prolonged lag period of cell growth. This indicates 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 genes and cold-shock adaptation. An 11-base common sequence (cold box) was found in the 5' UTRs of cspA, cspB, and csdA mRNAs. Indeed, the 25-base sequence within the 5' UTR of the cspA mRNA containing the cold-box sequence was able to prolong CspA production at 15 degrees C. We propose that a putative repressor binds to the cold-box sequence of the cold-shock mRNAs during the adaptive process and this binding in turn blocks the transcription of the cold-shock genes or destabilizes their mRNAs. CspA appears to promote either directly or indirectly the repressor function.
Jiang
W
W
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854, USA.
Fang
L
L
Inouye
M
M
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D001483:Base Sequence; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D003080:Cold Temperature; D016384:Consensus Sequence; D053487:DEAD-box RNA Helicases; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D020365:RNA Helicases; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C062260:cold shock protein CS7.4, Bacteria; C088840:deaD protein, E coli; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases