Part:BBa_K239006

Modified NarK promoter

Sequence contains 2 Fnr (one of which is modified), 1 Fis, 2 NarL binding sites and initiates transcription by RNAP sigma-70. Function: Switched on during anaerobic conditions (low oxygen level -> PoPS output).

Area of application: Detection of when the E.coli switches to anaerobic metabolism, or for oxygen dependent inducible systems.

It is designed to have better affinity to activated Fnr than the NarK promoter (BBa_K239005) and hence also stronger activity under anaerobic conditions. It is also shorter than the NarK promoter (BBa_K239005).

The optimal Fnr binding sequence is TTGAT-4N-ATCAA. (Spiro and Guest, 1990) For the native NarK promoter (BBa_K239005), the promoter-distal Fnr binding site differs in one base-pair from the optimal binding site. Modified NarK promoter (BBa_K239006) promoter-distal site has been re-written to the optimal sequence: TTGAT-AAAT-ATCAA.

Usage and Biology

Fnr is always present in the cell in largely constant amounts. (Spiro and Guest, 1987) In vivo, during anaerobic conditions Fnr becomes activated reversibly. (Engel et al. 1991) During aerobic growth O2 inactivates Fnr by destroying its [4Fe-4S] cluster, which is essential for DNA binding. (Green et al. 1996)

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]