Mutations in the chloramphenicol acetyltransferase (S61G, Y105C) increase accumulated amounts and resistance in Pseudomonas aeruginosa.
A chloramphenicol acetyltransferase (catB7) gene containing two point mutations, 181A/G and 314A/G, has been recently reported to be a determinant for high-level chloramphenicol resistance phenotype in a Pseudomonas aeruginosa strain PAhcr1. The mutant CATB7 was further characterized in vitro and in vivo to elucidate the molecular basis of high-level resistance. CAT assay demonstrated that the mutant and wild-type recombinant CATB7 had similar specific activities. Dot blotting revealed that the accumulated amounts of CATB7 in P. aeruginosa strains PAO1 and PAhcr1 were proportionate to the respective anti-chloramphenicol level. Site-directed mutagenesis showed that G61S and Y105C contributed synergistically to the PAhcr1 resistance phenotype. It could be proposed that the mutant CATB7 was more structurally stable than catalytically efficient as a chloramphenicol resistance determinant in PAhcr1.
Wang
Jian
J
School of Life Science & Technology, Shanghai Jiaotong University, No. 800 Dong-Chuan Road, Shanghai 200240, China.
Liu
Jian-Hua
JH
D000105:Acetyl Coenzyme A / Q000378:metabolism; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002701:Chloramphenicol / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002702:Chloramphenicol Resistance / Q000235:genetics*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D002701:Chloramphenicol; D000105:Acetyl Coenzyme A; D015500:Chloramphenicol O-Acetyltransferase