FNR

FNR is a protein that is involved in the anaerobic regulation of bacteria. It is a global transcription factor that is found in Escherichia coli and other Enterobacteriaceae. FNR stands for "fumarate and nitrate reduction regulatory protein", which indicates its role in the regulation of gene expression in response to oxygen levels.

Structure

FNR is a monomer that can exist in two states: an active, dimeric form and an inactive, monomeric form. The active form of FNR contains a 4Fe-4S cluster, which is sensitive to oxygen. When oxygen is present, the cluster is oxidized and the protein becomes inactive. In the absence of oxygen, the cluster is reduced and the protein becomes active.

Function

The primary function of FNR is to regulate the expression of genes involved in anaerobic metabolism. When oxygen levels are low, FNR activates the transcription of genes involved in the utilization of alternative electron acceptors, such as nitrate and fumarate. In addition, FNR represses the transcription of genes involved in aerobic metabolism.

Role in Disease

While FNR is essential for the survival of bacteria in anaerobic conditions, it can also contribute to the pathogenicity of certain bacteria. For example, in Salmonella enterica, FNR regulates the expression of genes involved in the invasion of host cells.

See Also

• Transcription factor
• Anaerobic respiration
• Gene expression

References

FNR Resources
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