A role of ygfZ in the Escherichia coli response to plumbagin challenge.
Plumbagin is found in many herbal plants and inhibits the growth of various bacteria. Escherichia coli strains are relatively resistant to this drug. The mechanism of resistance is not clear. Previous findings showed that plumbagin treatment triggered up-regulation of many genes in E. coli including ahpC, mdaB, nfnB, nfo, sodA, yggX and ygfZ. By analyzing minimal inhibition concentration and inhibition zones of plumbagin in various gene-disruption mutants, ygfZ and sodA were found critical for the bacteria to resist plumbagin toxicity. We also found that the roles of YgfZ and SodA in detoxifying plumbagin are independent of each other. This is because of the fact that ectopically expressed SodA reduced the superoxide stress but not restore the resistance of bacteria when encountering plumbagin at the absence of ygfZ. On the other hand, an ectopically expressed YgfZ was unable to complement and failed to rescue the plumbagin resistance when sodA was perturbed. Furthermore, mutagenesis analysis showed that residue Cys228 within YgfZ fingerprint region was critical for the resistance of E. coli to plumbagin. By solvent extraction and HPLC analysis to follow the fate of the chemical, it was found that plumbagin vanished apparently from the culture of YgfZ-expressing E. coli. A less toxic form, methylated plumbagin, which may represent one of the YgfZ-dependent metabolites, was found in the culture supernatant of the wild type E. coli but not in the ΔygfZ mutant. Our results showed that the presence of ygfZ is not only critical for the E coli resistance to plumbagin but also facilitates the plumbagin degradation.
Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, 112 Taiwan.
Ching-Nan
CN
Lin
Wan-Jr
WJ
Syu
Wei-Sheng W
WS
Sun
Jenn-Wei
JW
Chen
Tai-Hung
TH
Chen
Ming-Jaw
MJ
Don
Shao-Hung
SH
Wang
D000595:Amino Acid Sequence; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009285:Naphthoquinones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D016415:Sequence Alignment; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D009285:Naphthoquinones; C509203:YgfZ protein, E coli; D013481:Superoxides; C095500:SodA protein, Bacteria; D013482:Superoxide Dismutase; C014758:plumbagin