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. Author manuscript; available in PMC: 2015 Apr 1.
Published in final edited form as: J Inorg Biochem. 2013 Nov 15;0:118–126. doi: 10.1016/j.jinorgbio.2013.11.003

Figure 3.

Figure 3

The mechanism of SigL regulation. The membrane-associated anti-σ factor, RslA, contains a conserved cytosolic ZAS (HXXXCXXC) motif, which coordinates a structural Zn2+ ion under reducing conditions. SigL function is inhibited through complex formation occluding SigL’s predicted -35 promoter binding domain (PDB code 3HUG). Upon exposure to oxidative stress, the two cysteines of the CXXC motif (Cys54 and Cys57) form a disulfide bond, releasing the Zn2+ ion and leading to a conformational change in RslA. This conformational change results in the dissociation of the RslA/SigL complex, allowing SigL to interact with RNA polymerase and upregulate target genes.