Transcriptional analysis of padR and usp1 in recombinant E. coli strains and corresponding SDS-PAGE of protein extracts. (A) Northern blot with RNA extract from noninduced (NI) and 1.2 mM p-coumaric acid 10-min-induced (I) cells. (B) Northern blot with RNA extract from 1 mM IPTG-induced (+) or not induced (−) cells. The 600- and 1,300-base bands correspond to the usp1 and padR-usp1 transcripts, respectively, while “Smear” probably represents degradative products from the 1,300-base transcript. (C) DNA sequence upstream of usp1 indicating the −35 and −10 boxes that could serve as a promoter for usp1 in the recombinant E. coli strains pLOCPAD and pERU. (D) SDS-PAGE analysis of crude protein extracts from the recombinant E. coli strains. pET28a+, E. coli TG1 with the vector pET28a+; I, 1.2 mM p-coumaric acid-induced cell extracts; - and +, noninduced (−) and 1 mM IPTG-induced (+) cell extract. M, molecular mass standards.