RT Journal Article SR Electronic(1) A1 Belin, Pascal A1 Boquet, Paul LouisYR 1994 T1 The Escherichia coli dsbAgene is partly transcribed from the promoter of a weakly expressed upstream gene JF Microbiology, VO 140 IS 12 SP 3337 OP 3348 DO https://doi.org/10.1099/13500872-140-12-3337 PB Microbiology Society, SN 1465-2080, AB The dsbAgene of Escherichia coliencodes a periplasmic enzyme which catalyses disulfide bond formation. Analysis of its surrounding DNA region showed that it is preceded by an open reading frame, orfA, of 984 nucleotides. The intergenic region (19 nucleotides) carries no typical transcription termination signals. dsbAis transcribed from two promoters, the first (P1) lies in the distal part of orfA, and the second (P2) just upstream from orfA. Using a plasmid-borne dsbA:: TnphoAfusion and an orfA:: ω insertion, each promoter was shown to contribute equally to dsbAtranscription. The disruption of the single chromosomal copy of orfAby ω more drastically reduced the amount of DsbA in the periplasmic space. Such a reduction of the DsbA pool, however, did not change the activities of the AppA, Agp and PhoA periplasmic phosphatases, which all require disulfide bond formation, even when the enzymes were produced from multicopy recombinant plasmids. Thus, in a wild-type strain, DsbA is far from being in limiting amounts for physiological requirements. The orfAgene product was identified as a weakly expressed 39 kDa cytoplasmic protein, but it is not involved in the overall mechanism of disulfide bond formation., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-140-12-3337