A combination of sbmA and tolC mutations in Escherichia coli K-12 Tn10–carrying strains results in hypersusceptibility to tetracycline.

RICARDO E. DE CRISTOBAL; PAULA A. VINCENT; RAÚL A. SALOMÓN

JOURNAL OF BACTERIOLOGY

ASMpress

Año: 2008 vol. 190 p. 1491 - 1494

0021-9193

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 ug/ml to resistance at 40 ug/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 ug/ml. Inactivation of sbmA alone partially inhibited high-level tetracycline resistance, from resistance at 200 ug/ml to resistance at 120 ug/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.