1.13.11.8 - 1.13.11.8 expression in Escherichia coli 1.13.11.8 gene organization of the PCA45 pathway genes in strain E6, overview. Identification of the pmd promoter region, the transcription start site of the pmd operon is a thymine 167 nt upstream of the pmdU start codon, overview 1.13.11.8 genetic organization Comamonas-type with a single operon 1.13.11.8 genetic organization Sphingobium-type with several transcriptional units 1.13.11.8 recombinant expression of His6-tagged wild-type and mutant enzymes in Escherichia coli strain DH5alpha