Part:BBa_M33002
CDS for Fnr-LH28 protein, activates narGp in presence of nitrate.
fnr (fumarate nitrate reductase) is a DNA-binding protein that is a global regulator involved in cellular respiration and metabolism during times of anaerobic cell growth (Melville et al 1996). The part contains a single missense LH28 mutation to allow it to operate under aerobic conditions. Cytoplasmic Fnr-LH28 protein created by the gene can bind to a regulatory region of the narG promoter to "enable nitrate-dependent expression"(Li, Rabi, DeMoss 1985) of what is downstream of narGp. It can thus be used in conjunction with BBa_M33001, the narG promoter in order to create a nitrate biosensor functional in oxygen.
As an iron-sulfur protein, fnr depends on its [4Fe-4S][+2] cluster to have functional ability in the cell. Upon exposure to oxygen, fnr undergoes a "rapid [4Fe-4S][+2] to [2Fe-2S][+2] cluster conversion...[and a] concomitant loss in site-specific DNA binding and dimerization" (Bates et al 2000), which results in fnr losing its acitvity in the cell in aerobic conditions.However, a substitution of Histidine on the 28th amino acid of fnr (which is Leucine in regular fnr) results in a protein that is functional in aerobic growth conditions. The new mutant protein is called L28H-fnr in the literature. It is suggested that this added functionality of L28H-fnr occurs because the "His-28 substitution appears to stabilize the [4Fe-4S][+2] cluster of FNR-L28H in the presence of O2" (Bates et al 2000).
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
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