An integrative approach combining biophysical and microbiological methods was used to characterize the antibiotic translocation through the outer membrane of Providencia stuartii. Two novel members of the General Bacterial Porin family of Enterobacteriaceae, named OmpPst1 and OmpPst2, were identified in P. stuartii. In the presence of ertapenem (ERT), cefepime (FEP), and cefoxitin (FOX) in growth media, several resistant derivatives of P. stuartii ATCC 29914 showed OmpPst1-deficiency. These porin-deficient strains showed significant decrease of susceptibility to beta-lactam antibiotics. OmpPst1 and OmpPst2 were purified to homogeneity and reconstituted into planar lipid bilayers to study their biophysical characteristics and their interactions with beta-lactam molecules. Determination of beta-lactam translocation through OmpPst1 and OmpPst2 indicated that the strength of interaction decreased in the order of ertapenem >> cefepime > cefoxitin. Moreover, the translocation of these antibiotics through OmpPst1 was more efficient than through OmpPst2. Heterologous expression of OmpPst1 in the porin-deficient E. coli strain BL21(DE3) omp8 was associated with a higher antibiotic susceptibility of the E. coli cells to beta-lactams compared with expression of OmpPst2. All our data enlighten the involvement of porins in the resistance of P. stuartii to beta-lactam antibiotics.

Role of providencia stuartii porins in beta-lactam resistance

CECCARELLI, MATTEO;
2010

Abstract

An integrative approach combining biophysical and microbiological methods was used to characterize the antibiotic translocation through the outer membrane of Providencia stuartii. Two novel members of the General Bacterial Porin family of Enterobacteriaceae, named OmpPst1 and OmpPst2, were identified in P. stuartii. In the presence of ertapenem (ERT), cefepime (FEP), and cefoxitin (FOX) in growth media, several resistant derivatives of P. stuartii ATCC 29914 showed OmpPst1-deficiency. These porin-deficient strains showed significant decrease of susceptibility to beta-lactam antibiotics. OmpPst1 and OmpPst2 were purified to homogeneity and reconstituted into planar lipid bilayers to study their biophysical characteristics and their interactions with beta-lactam molecules. Determination of beta-lactam translocation through OmpPst1 and OmpPst2 indicated that the strength of interaction decreased in the order of ertapenem >> cefepime > cefoxitin. Moreover, the translocation of these antibiotics through OmpPst1 was more efficient than through OmpPst2. Heterologous expression of OmpPst1 in the porin-deficient E. coli strain BL21(DE3) omp8 was associated with a higher antibiotic susceptibility of the E. coli cells to beta-lactams compared with expression of OmpPst2. All our data enlighten the involvement of porins in the resistance of P. stuartii to beta-lactam antibiotics.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11584/21930
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