Iron-sulfur (Fe-S) clusters are essential for viability of all living organisms. More than 150 proteins are thought to require an Fe/S cluster for their activity and among them, 7 are involved in gene regulation. They are mainly involved in adaptation to changing environments thanks to the capacity of Fe-S clusters to act as sensors of various environmental stimuli such as redox changes, oxidative and nitrosative stresses, iron limitation, antibiotic, metal contamination, etc. The last uncharacterized Fe/S cluster regulator is YeiL. Little is known about this regulator and only one princeps study has been published. Biochemical studies have shown that it is a 4Fe-4S regulator and further functional studies have shown that it plays a role for bacterial survival during nitrogen starvation.
A transcriptomic study allowed us to show that the YeiL regulator is mainly involved in repressing nitrate respiration and activating genes involved in acid stress resistance. Nitrate respiration generates nitric oxide (NO) as a byproduct. NO is responsible for S-nitrosylation of cysteine chelating Fe/S clusters and it could thus be involved in modification of the YeiL regulatory activity. In order to test this hypothesis we would like to study the role of the Fe/S cluster in the regulatory activity of YeiL. We have generated a new allele of the yeiL gene wich encodes a protein that is no more able to bind Fe/S cluster (the four coordinating cysteine residues has been replaced by alanine). Our preliminary results, based of expression level of some selected YeiL-regulated genes, suggest that the apo-form of the regulator could be the active form.
A high throughput study of the YeiL variant could allow us to compare the transcriptome of the wild type (already done with Biomics) and the apo-form of the regulator to decipher its role and the environmental conditions that require this still misstudied regulator.
