TY - JOUR
T1 - nalB-type mutations causing the overexpression of the MexAB-OprM efflux pump are located in the mexR gene of the Pseudomonas aeruginosa chromosome
AU - Saito, Kohjiro
AU - Yoneyama, Hiroshi
AU - Nakae, Taiji
N1 - Funding Information:
This study was supported in part by grants from the Ministry of Education of Japan, Science, Sport and Culture, the Ministry of Health and Welfare’s Emerging and Re-emerging Infectious Diseases Program, the Japan Society for Promotion of Science, Tokai University School of Medicine’s Project Research, and a Sasakawa Scientific Research Grant from The Japan Science Society.
PY - 1999/10/1
Y1 - 1999/10/1
N2 - Two mutations, one at the nalB and the other at the mexR locus, in the Pseudomonas aeruginosa chromosome are known to cause overexpression of the MexAB-OprM efflux pump. Based on the following results, we concluded that nalB is the mutation that has occurred within the mexR gene of the P. aeruginosa chromosome. (i) Nucleotide sequencing of the mex operon upstream region of 21 independent nalB-type mutants including the original nalB9 revealed that all the mutations were located within the mexR gene. The mutations were classified into three different groups and nine types including single base substitutions, single base deletions and base insertions. (ii) Substitution of the mutant mexR with the wild-type mexR and replacement of the wild-type mexR with a defined mexR mutation resulted in the expression of wild-type and nalB-type MexAB-OprM respectively, which was confirmed by testing the antibiotic susceptibility and β-galactosidase activity of the mexA-lacZ translational fusion. Copyright (C) 1999 Federation of European Microbiological Societies.
AB - Two mutations, one at the nalB and the other at the mexR locus, in the Pseudomonas aeruginosa chromosome are known to cause overexpression of the MexAB-OprM efflux pump. Based on the following results, we concluded that nalB is the mutation that has occurred within the mexR gene of the P. aeruginosa chromosome. (i) Nucleotide sequencing of the mex operon upstream region of 21 independent nalB-type mutants including the original nalB9 revealed that all the mutations were located within the mexR gene. The mutations were classified into three different groups and nine types including single base substitutions, single base deletions and base insertions. (ii) Substitution of the mutant mexR with the wild-type mexR and replacement of the wild-type mexR with a defined mexR mutation resulted in the expression of wild-type and nalB-type MexAB-OprM respectively, which was confirmed by testing the antibiotic susceptibility and β-galactosidase activity of the mexA-lacZ translational fusion. Copyright (C) 1999 Federation of European Microbiological Societies.
KW - Antibiotic resistance
KW - Efflux pump
KW - Gene regulation
KW - Multidrug resistance
KW - Pseudomonas
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U2 - 10.1016/S0378-1097(99)00394-8
DO - 10.1016/S0378-1097(99)00394-8
M3 - Article
C2 - 10481088
AN - SCOPUS:0032821426
VL - 179
SP - 67
EP - 72
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
SN - 0378-1097
IS - 1
ER -