Regulation of proteolysis in Escherichia coli cells by antisense RNA of htpR gene.
A new vector has been constructed on the basis of plasmid pCQV2 containing thermoinducible regulatory elements of bacteriophage lambda. The vector makes it possible to combine an inducible synthesis of foreign proteins with negative control of intracellular proteolysis. The principle employed for the construction of the plasmid implies the regulation of gene expression by antisense RNAs. In the SalI restriction site of pCQV2 a fragment of htpR gene encoding the N-terminal region of the polypeptide has been cloned in opposite orientation. At 42 degrees C transcription from the PR promoter of the plasmid is initiated, resulting in the synthesis of htpR antisense RNA. The product of htpR gene is known to be responsible for positive regulation of transcription of at least three genes encoding proteases lon, groEL, and groES. Inactivation of the htpR transcript due to its complementary pairing with the antisense RNA hinders the synthesis of proteases under temperature stress conditions, thus leading to the reduction in the rate of proteolysis of abnormal proteins.