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Table 1 Phenotypic profiles of QacA tyrosine mutants

From: Functional analyses reveal an important role for tyrosine residues in the staphylococcal multidrug efflux protein QacA

QacA mutation QacA expression (% wt QacA)c minimum inhibitory concentration (μg ml-1)a.b
   monovalent substrates bivalent substrates
   dyes Qacsd Bg Di
   Et PyY Bc Dc Ch Dd
wt QacA 100 1200 500 50 350 12 300
vector N/A 400 50 30 100 2 100
Y63V 86 200 50 30 150 4 100
Y63F 50 1400 400 50 250 12 300
Y315A 64 800 500 50 300 12 400
Y315F 75 1000 500 50 300 12 300
Y358S 80 600 400 50 100 8 200
Y358F 34 1400 400 50 300 16 300
Y366A 106 1200 300 50 100 12 300
Y366V 50 1200 400 50 300 12 300
Y366F 99 800 500 50 300 12 400
Y410A 132 400 50 45 100 3 100
Y410V 67 200 50 30 100 7 300
Y410F 58 200 100 50 250 12 300
Y429S 57 200 200 30 250 4 100
Y429F 32 1400 500 60 300 14 400
Y501V 36 800 500 50 300 12 300
Y501F 47 1200 500 50 350 12 400
  1. a MIC values were determined in E. coli BHB2600 cells expressing wild-type QacA or a mutant derivative and represent the lowest concentration of substrate required to fully inhibit bacterial growth.
  2. b MIC experiments were conducted in at least triplicate and the median value is presented.
  3. c QacA protein expression levels are the average of two repeat experiments.
  4. d Abbreviations: Qacs, quaternary ammonium compounds; Bg, biguanidines; Di, diamidines; Et, ethidium; PyY, pyronin Y; Bc, benzalkonium; Dc, dequalinium; Ch, chlorhexidine; Dd, diamidinodiphenylamine.