In the absence of functional RqlI the PRTase domain of RqlH elicits genotoxic effects.

Model depicts a possible function for the rqlHI operon. (A) The PRTase domain of RqlH alters a nucleotide (red) within the bacterial genome, and (B) RqlI functions to resolve this modified nucleotide (light blue) with the help of the helicase domain of RqlH. The resolution event could include further modification of the nucleotide or restoring the nucleotide to its original structure. (C) In the absence of RqlI, the PRTase domain of RqlH continues to alter chromosomal nucleotides, but these modifications are not resolved, producing effects that are toxic to the bacteria, resulting in the induction of the SOS response, cell elongation, growth inhibition, heightened sensitivity to DNA damaging agents, and increased mutation rates. Many of these phenotypes are intensified under low oxygen conditions for unknown reasons.