[Effect of temperature on the expression of penicillin G acylase gene at the level of post-translational processing]

The expression of penicillin G acylase (PGA) gene is sensitive to temperature. Cells of E. coli DH 5 alpha harboring a plasmid pWGA carrying a gene for PGA produce active PGA at low level at 37 degrees C, but can synthesize significant amount of the enzyme below 30 degrees C. Active PGA is formed from a 94 KD precursor processed through remove of a signal peptide and a spacer peptide to yield an enzyme that contain a 23 KD (alpha) and 65 KD (beta) subunit. This paper reported the effect of temperature on transcription, translation, and post-translational processing of PGA gene expression. We detected the transcription of PGA gene by Northern blot, and found the amount of PGA mRNA at 37 degrees C much more than that 30 degrees C when the cells of DH 5 alpha (pWGA) were cultured. It is evident that the precursor processing step(s) is sensitive to temperature.