Carbapenem resistance in cystic fibrosis strains of Pseudomonas aeruginosa as a result of amino acid substitutions in porin OprD.
The aim of this work was to investigate the impact of single amino acid substitutions occurring in specific porin OprD on carbapenem resistance of cystic fibrosis (CF) strains of Pseudomonas aeruginosa. A PAO1ΔoprD mutant was complemented with the oprD genes from five carbapenem-resistant CF strains exhibiting very low amounts of mutated OprD porins in their outer membrane despite wild-type levels of oprD transcripts. Compared with wild-type porin from strain PAO1, single amino acid substitutions S403P (in periplasmic loop 8), Y242H, S278P and L345P (in β-sheets 10, 12 and 14, respectively) were found to result in reduced amounts of OprD in the outer membrane, increased carbapenem resistance, and slower growth in minimal medium containing gluconate, an OprD substrate, as the sole source of carbon and energy. This indicates that in CF strains of P. aeruginosa, loss of porin OprD may not only result from mutations downregulating the expression of or disrupting the oprD gene, but also from mutations generating deleterious amino acid substitutions in the porin structure.
Laboratoire de Bactériologie EA4266, Faculté de Médecine-Pharmacie, Université de Franche-Comté, Besançon, France.
Charlotte
C
Richardot
Laboratoire de Bactériologie EA4266, Faculté de Médecine-Pharmacie, Université de Franche-Comté, Besançon, France.
Patrick
P
Plésiat
Laboratoire de Bactériologie EA4266, Faculté de Médecine-Pharmacie, Université de Franche-Comté, Besançon, France.
Damien
D
Fournier
UMR8015, Laboratoire de Cristallographie et RMN biologiques, Paris, France.
Laura
L
Monlezun
UMR8015, Laboratoire de Cristallographie et RMN biologiques, Paris, France.
Isabelle
I
Broutin
Laboratoire de Bactériologie EA4266, Faculté de Médecine-Pharmacie, Université de Franche-Comté, Besançon, France. Electronic address: cllanesb@univ-fcomte.fr.
Catherine
C
Llanes
D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D003550:Cystic Fibrosis / Q000150:complications; D017353:Gene Deletion; D005816:Genetic Complementation Test; D005942:Gluconates / Q000378:metabolism; D006801:Humans; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D018272:Porins / Q000235:genetics* / Q000378:metabolism; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D003470:Culture Media; D005942:Gluconates; D050505:Mutant Proteins; D018272:Porins; C077157:OprD protein, Pseudomonas aeruginosa; C030691:gluconic acid
Carbapenem resistance; Cystic fibrosis; OprD porin; Pseudomonas aeruginosa