Gene structure and transcriptional regulation of dnaK and dnaJ genes from a psychrophilic bacterium, Colwellia maris.
The dnaK and dnaJ genes, encoding heat shock proteins, were cloned from a psychrophilic bacterium, Colwellia maris. Significant homology was evident comparing DnaK and DnaJ of the psychrophilile with the counterparts of mesophilic and thermophilic bacteria. In the DnaJ protein, three conserved regions of the Hsp40 family were observed. A putative promoter similar to the sigma32 consensus sequence was found upstream of the dnaK gene. The G+C content in the 5'-untranslated region of the dnaK gene was much lower than that in the corresponding region of mesophilic bacteria. Northern-blot analysis and primer-extension analysis showed that both genes were transcribed separately as monocistronic mRNAs. Following several temperature upshifts from 10 to 26 degrees C, maximum induction of the dnaK and dnaJ mRNAs was detected at 20 degrees C, suggesting that this temperature induces the heat shock response in this bacterium. In addition, the level of the induction of the dnaJ gene was much lower than that of the dnaK gene. These findings together revealed several specific features of the heat shock response at a relatively low temperature in psychrophiles.
Yamauchi
Seiji
S
Graduate School of Science and Engineering, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan.
Okuyama
Hidetoshi
H
Nishiyama
Yoshitaka
Y
Hayashi
Hidenori
H
D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004777:Environment; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D006360:Heat-Shock Proteins