RETRACTION
Volume 193, no. 5, p. 1086–1089, 2011. We were informed by Kevin Young and Gang Li (Microbiology 160:2079–2088, 2014) that strain H41 is not a tolC mutant as we had described. We have sequenced strain H41 and confirm that it is not a tolC mutant. Rather, the observed phenotype is due to a point mutation in crp and the subsequent A144T substitution in the Crp protein that reduces the requirement for cyclic AMP. Since the conclusions of our paper are based on the presumed tolC mutation, they are no longer valid and we regretfully retract the manuscript. Klaus Hantke assumes full responsibility for this error.