Tat-dependent amidases are required for Salmonella resistance to protamine and vancomycin. A, percentage survival of wild-type (14028s), phoP (YS11590), tatC (YS13007), amiB (YS13764), amiA (YS13629), amiC (YS13630), and amiA amiC (YS13766) strains after incubation with protamine (0 or 1.2 mg/ml). Each strain carries pUHE21 (vector). Additionally, amiA and amiA amiC each carry pamiA (pYS2011), whereas amiC and amiA amiC each carry pamiC (pYS2012). B, percentage survival of wild-type, tatC, and amiA amiC strains after incubation with vancomycin (0 or 0.5 mg/ml). Each strain carries pUHE21. Additionally, tatC mutant carries pBAD-tatC, whereas amiA amiC mutant carries pamiA or pamiC. Data correspond to mean values from at least two independent experiments performed in duplicate. Error bars, S.D.