TY - JOUR
T1 - A novel promoter architecture for microaerobic activation by the anaerobic transcription factor FNR
AU - Marshall, F
AU - Messenger, S
AU - Wyborn, N
AU - Guest, J
AU - Wing, Helen
AU - Busby, Stephen
AU - Green, J
PY - 2001/2/1
Y1 - 2001/2/1
N2 - The yfiD gene of Escherichia coli has an unusual promoter architecture in which an FNR dimer located at -93.5 inhibits transcription activation mediated by another FNR dimer bound at the typical class II position (-40.5). In vitro transcription from the yfiD promoter indicated that FNR alone can downregulate yfiD expression. Analysis of yfiD::lac reporters showed that five turns of the DNA helix between FNR sites was optimal for downregulation. FNR heterodimers, in which one subunit carried a defective repression surface, revealed that the upstream subunit of the -40.5 dimer and the downstream subunit of the -93.5 dimer were most important for downregulating yfiD expression. Deletion of the C-terminal domain of the alpha-subunit of RNA polymerase (RNAP) did not affect FNR-mediated repression, suggesting that repression is mediated through FNR-FNR and not FNR-RNAP interactions. Maximum yfiD::lac expression was observed in cultures exposed to 10 microM oxygen. More or less oxygen reduced expression dramatically. This pattern of response was dependent on the combination of a high-affinity site at the activating class II position and a lower affinity site at the upstream position.
AB - The yfiD gene of Escherichia coli has an unusual promoter architecture in which an FNR dimer located at -93.5 inhibits transcription activation mediated by another FNR dimer bound at the typical class II position (-40.5). In vitro transcription from the yfiD promoter indicated that FNR alone can downregulate yfiD expression. Analysis of yfiD::lac reporters showed that five turns of the DNA helix between FNR sites was optimal for downregulation. FNR heterodimers, in which one subunit carried a defective repression surface, revealed that the upstream subunit of the -40.5 dimer and the downstream subunit of the -93.5 dimer were most important for downregulating yfiD expression. Deletion of the C-terminal domain of the alpha-subunit of RNA polymerase (RNAP) did not affect FNR-mediated repression, suggesting that repression is mediated through FNR-FNR and not FNR-RNAP interactions. Maximum yfiD::lac expression was observed in cultures exposed to 10 microM oxygen. More or less oxygen reduced expression dramatically. This pattern of response was dependent on the combination of a high-affinity site at the activating class II position and a lower affinity site at the upstream position.
UR - http://www.scopus.com/inward/record.url?scp=0035136782&partnerID=8YFLogxK
U2 - 10.1046/j.1365-2958.2001.02262.x
DO - 10.1046/j.1365-2958.2001.02262.x
M3 - Article
C2 - 11169114
SN - 1365-2958
VL - 39
SP - 747
EP - 753
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 3
ER -