aph(3′)-IIb, a Gene Encoding an Aminoglycoside-Modifying Enzyme, Is under the Positive Control of Surrogate Regulator HpaA
AUTOR(ES)
Zeng, Lin
FONTE
American Society for Microbiology
RESUMO
Pseudomonas aeruginosa harbors a chromosomal aminoglycoside phosphotransferase gene, aph(3′)-IIb, which confers P. aeruginosa resistance to several important aminoglycoside antibiotics, including kanamycin A and B, neomycin B and C, butirosin, and seldomycin F5. The aph(3′)-IIb gene has been found to be regulated by an AraC-type transcriptional regulator (HpaA) encoded by a gene located upstream of the aph(3′)-IIb gene. In the presence of 4-hydroxyphenylacetic acid (4-HPA), HpaA activates the expression of aph(3′)-IIb as well as that of the hpa regulon which encodes metabolic enzymes for the utilization of 4-HPA. hpaA and aph(3′)-IIb form an operon, and in response to the presence of 4-HPA, the wild-type P. aeruginosa strain PAK (but not its hpaA mutant strain) displays increased resistance to neomycin. A survey of 39 clinical and 19 environmental isolates of P. aeruginosa demonstrated in all of them the presence of an hpaA-aph gene cluster, while 56 out of the 58 isolates are able to utilize the 4-HPA as a sole carbon source, suggesting a feature common to P. aeruginosa strains. Interestingly, a larger portion of clinical isolates than environmental isolates showed 4-HPA-induced resistance to neomycin. The aph(3′)-IIb gene product is likely to function as a metabolic enzyme which has a cross-reactivity with aminoglycosides. These findings provide new insight into the possible mechanism of P. aeruginosa antibiotic resistance.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=296182Documentos Relacionados
- Nucleotide sequence of the transposon Tn7 gene encoding an aminoglycoside-modifying enzyme, 3"(9)-O-nucleotidyltransferase.
- Nomenclature of Genes Encoding Aminoglycoside-Modifying Enzymes
- Gene homogeneity for aminoglycoside-modifying enzymes in gram-positive cocci.
- The prevalence of aminoglycoside-modifying enzyme genes (aac (6')-I, aac (6')-II, ant (2")-I, aph (3')-VI) in Pseudomonas aeruginosa
- Effect of aminoglycoside concentration on reaction rates of aminoglycoside-modifying enzymes.