This Article Full Text Full Text (PDF) Other Versions of this Article: JB.01844-07v1 190/4/1491    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by de Cristóbal, R. E. Articles by Salomón, R. A. PubMed PubMed Citation Articles by de Cristóbal, R. E. Articles by Salomón, R. A.

A Combination of sbmA and tolC Mutations in Escherichia coli K-12 Tn10-Carrying Strains Results in Hypersusceptibility to Tetracycline

Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán, and Instituto de Química Biológica Dr. Bernabé Bloj, Chacabuco 461, 4000 San Miguel de Tucumán, Tucumán, Argentina

Received 22 November 2007/ Accepted 1 December 2007

Previously, we demonstrated that Escherichia coli tolC mutations reduce the high-level resistance to tetracycline afforded by the transposon Tn10-encoded TetA pump from resistance at 200 µg/ml to resistance at 40 µg/ml. In this study, we found that the addition of an sbmA mutation to a tolC::Tn10 mutant exacerbates this phenotype: the double mutant did not form colonies, even in the presence of tetracycline at a concentration as low as 5 µg/ml. Inactivation of sbmA alone partially inhibited high-level tetracycline resistance, from resistance at 200 µg/ml to resistance at 120 µg/ml. There thus appears to be an additive effect of the mutations, resulting in almost complete suppression of the phenotypic expression of Tn10 tetracycline resistance.

Published ahead of print on 14 December 2007.