CspA, CspB, and CspG, Major Cold Shock Proteins of Escherichia coli , Are Induced at Low Temperature under Conditions That Completely Block Protein Synthesis

Abstract

ABSTRACT CspA, CspB, and CspG, the major cold shock proteins of Escherichia coli , are dramatically induced upon temperature downshift. In this report, we examined the effects of kanamycin and chloramphenicol, inhibitors of protein synthesis, on cold shock inducibility of these proteins. Cell growth was completely blocked at 37°C in the presence of kanamycin (100 μg/ml) or chloramphenicol (200 μg/ml). After 10 min of incubation with the antibiotics at 37°C, cells were cold shocked at 15°C and labeled with [ 35 S]methionine at 30 min after the cold shock. Surprisingly, the synthesis of all these cold shock proteins was induced at a significantly high level virtually in the absence of synthesis of any other protein, indicating that the cold shock proteins are able to bypass the inhibitory effect of the antibiotics. Possible bypass mechanisms are discussed. The levels of cspA and cspB mRNAs for the first hour at 15°C were hardly affected in the absence of new protein synthesis caused either by antibiotics or by amino acid starvation.