Identification of Pseudomonas aeruginosa genes crucial for hydrogen peroxide resistance.
An opportunistic human pathogen, Pseudomonas aeruginosa, contains the major catalase KatA, which is required to cope with oxidative and osmotic stresses. As an attempt to uncover the H2O2-dependent regulatory mechanism delineating katA gene expression, four prototrophic H2O2-sensitive mutants were isolated from about 1,500 TnphoA mutant clones of P. aeruginosa strain PA14. Arbitrary PCR and direct cloning of the transposon insertion sites revealed that one insertion is located within the katA coding region and two are within the coding region of oxyR, which is responsible for transcriptional activation of several antioxidant enzyme genes in response to oxidative challenges. The fourth insertion was within PA3815 (IscR), which encodes a homolog of the Escherichia coli iron-sulfur assembly regulator, IscR. The levels of catalase and SOD activities were significantly reduced in the iscR mutant, but not in the oxyR mutant, during the normal planktonic culture conditions. These results suggest that both IscR and OxyR are required for the optimal resistance to H2O2, which involves the expression of multiple antioxidant enzymes including KatA.
Department of Life Science, Sogang University, Seoul 121-742, Korea.
Young-Seok
YS
Choi
Dong-Ho
DH
Shin
In-Young
IY
Chung
Seol-Hee
SH
Kim
Yun-Jeong
YJ
Heo
You-Hee
YH
Cho
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016254:Mutagenesis, Insertional; D010544:Peroxidases / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics*; D013482:Superoxide Dismutase / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; C524857:OxyR protein, Pseudomonas aeruginosa; D015534:Trans-Activators; D014157:Transcription Factors; D006861:Hydrogen Peroxide; D010544:Peroxidases; C081610:catalase-peroxidase, bacteria; D013482:Superoxide Dismutase