title: Determinants of Antibacterial Spectrum and Resistance Potential of the Elongation Factor G Inhibitor Argyrin B in Key Gram-Negative Pathogens.
abstract: Argyrins are natural products with antibacterial activity against Gram-negative pathogens, such asPseudomonas aeruginosa,Burkholderia multivorans, andStenotrophomonas maltophiliaWe previously showed that argyrin B targets elongation factor G (FusA). Here, we show that argyrin B activity againstP. aeruginosaPAO1 (MIC = 8 μg/ml) was not affected by deletion of the MexAB-OprM, MexXY-OprM, MexCD-OprJ, or MexEF-OprN efflux pump. However, argyrin B induced expression of MexXY, causing slight but reproducible antagonism with the MexXY substrate antibiotic ciprofloxacin. Argyrin B activity againstEscherichia coliincreased in a strain with ninetolCefflux pump partner genes deleted. Complementation experiments showed that argyrin was effluxed by AcrAB, AcrEF, and MdtFX. Argyrin B was inactive againstAcinetobacter baumanniiDifferences betweenA. baumanniiandP. aeruginosaFusA proteins at key residues for argyrin B interaction implied that natural target sequence variation impacted antibacterial activity. Consistent with this, expression of the sensitiveP. aeruginosaFusA1 protein inA. baumanniiconferred argyrin susceptibility, whereas resistant variants did not. Argyrin B was active againstS. maltophilia(MIC = 4 μg/ml). Spontaneous resistance occurred at high frequency in the bacterium (circa 10-7), mediated by mutational inactivation offusA1rather than by amino acid substitutions in the target binding region. This strongly suggested that resistance occurred at high frequency through loss of the sensitive FusA1, leaving an alternate argyrin-insensitive elongation factor. Supporting this, an additionalfusA-like gene (fusA2) is present inS. maltophiliathat was strongly upregulated in response to mutational loss offusA1.
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Adriana K
authors.initials: AK
authors.lastname: Jones
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Woods
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Takeoka
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Shen
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Jun-Rong
authors.initials: JR
authors.lastname: Wei
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Caughlan
authors.affiliation: Infectious Diseases Area, Novartis Institutes for Biomedical Research, Emeryville, California, USA charlesr.dean@novartis.com.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Dean
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019117:Burkholderia / Q000187:drug effects / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009842:Oligopeptides / Q000494:pharmacology*; D020653:Peptide Elongation Factor G / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism; D020615:Stenotrophomonas maltophilia / Q000187:drug effects / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D009842:Oligopeptides; D020653:Peptide Elongation Factor G; C467071:argyrin B
keywords: Acinetobacter; Gram negative; Pseudomonas aeruginosa; Stenotrophomonas; antibacterial; argyrin; elongation factor G; natural product