Dataset Information

Penicillin Binding Protein 1 Is Important in the Compensatory Response of Staphylococcus aureus to Daptomycin-Induced Membrane Damage and Is a Potential Target for ?-Lactam-Daptomycin Synergy.

ABSTRACT: The activity of daptomycin (DAP) against methicillin-resistant Staphylococcus aureus (MRSA) is enhanced in the presence of ?-lactam antibiotics. This effect is more pronounced with ?-lactam antibiotics that exhibit avid binding to penicillin binding protein 1 (PBP1). Here, we present evidence that PBP1 has a significant role in responding to DAP-induced stress on the cell. Expression of the pbpA transcript, encoding PBP1, was specifically induced by DAP exposure whereas expression of pbpB, pbpC, and pbpD, encoding PBP2, PBP3, and PBP4, respectively, remained unchanged. Using a MRSA COL strain with pbpA under an inducible promoter, increased pbpA transcription was accompanied by reduced susceptibility to, and killing by, DAP in vitro. Exposure to ?-lactams that preferentially inactivate PBP1 was not associated with increased DAP binding, suggesting that synergy in the setting of anti-PBP1 pharmacotherapy results from increased DAP potency on a per-molecule basis. Combination exposure in an in vitro pharmacokinetic/pharmacodynamic model system with ?-lactams that preferentially inactivate PBP1 (DAP-meropenem [MEM] or DAP-imipenem [IPM]) resulted in more-rapid killing than did combination exposure with DAP-nafcillin (NAF) (nonselective), DAP-ceftriaxone (CRO) or DAP-cefotaxime (CTX) (PBP2 selective), DAP-cefaclor (CEC) (PBP3 selective), or DAP-cefoxitin (FOX) (PBP4 selective). Compared to ?-lactams with poor PBP1 binding specificity, exposure of S. aureus to DAP plus PBP1-selective ?-lactams resulted in an increased frequency of septation and cell wall abnormalities. These data suggest that PBP1 activity may contribute to survival during DAP-induced metabolic stress. Therefore, targeted inactivation of PBP1 may enhance the antimicrobial efficiency of DAP, supporting the use of DAP-?-lactam combination therapy for serious MRSA infections, particularly when the ?-lactam undermines the PBP1-mediated compensatory response.

SUBMITTER: Berti AD

PROVIDER: S-EPMC4704217 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Penicillin Binding Protein 1 Is Important in the Compensatory Response of Staphylococcus aureus to Daptomycin-Induced Membrane Damage and Is a Potential Target for β-Lactam-Daptomycin Synergy.

Berti Andrew D AD Theisen Erin E Sauer John-Demian JD Nonejuie Poochit P Olson Joshua J Pogliano Joseph J Sakoulas George G Nizet Victor V Proctor Richard A RA Rose Warren E WE

Antimicrobial agents and chemotherapy 20151102 1

The activity of daptomycin (DAP) against methicillin-resistant Staphylococcus aureus (MRSA) is enhanced in the presence of β-lactam antibiotics. This effect is more pronounced with β-lactam antibiotics that exhibit avid binding to penicillin binding protein 1 (PBP1). Here, we present evidence that PBP1 has a significant role in responding to DAP-induced stress on the cell. Expression of the pbpA transcript, encoding PBP1, was specifically induced by DAP exposure whereas expression of pbpB, pbpC, ...[more]

PMID: 26525797

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Project description:Exogenous spermine was reported to enhance the killing of methicillin-resistant Staphylococcus aureus (MRSA) by ?-lactams through a strong synergistic effect of unknown nature. Spermine alone also exerts an antimicrobial activity against S. aureus in a pH-dependent manner. MIC measurements revealed stronger effects of spermine under alkaline conditions, suggesting the nucleophilic property of spermine instead of its positive charge as the cause of adverse effects. A spontaneous suppressor mutant (MuM) of MRSA Mu50 was selected for spermine resistance and conferred complete abolishment of spermine-?-lactam synergy. In comparison to that in Mu50, the spermine MIC in MuM remained constant (64 mM) at pH 6 to 8; however, MuM, a heat-sensitive mutant, also grew in a very narrow pH range. Furthermore, MuM acquired a unique phenotype of vancomycin-spermine synergy. Genome resequencing revealed a 7-bp deletion in pbpB, which results in a truncated penicillin-binding protein 2 (PBP 2) without the transpeptidase domain at the C terminus while the N-terminal transglycosidase domain remains intact. The results of fluorescent Bocillin labeling experiments confirmed the presence of this defective PBP 2 in MuM. All the aforementioned phenotypes of MuM were reverted to those of Mu50 after complementation by the wild-type pbpB carried on a recombinant plasmid. The anticipated changes in cell wall metabolism and composition in MuM were evidenced by observations that the cell wall of MuM was more susceptible to enzyme hydrolysis and that MuM exhibited a lower level of autolytic activities. Pleiotropic alterations in gene expression were revealed by microarray analysis, suggesting a remarkable flexibility of MuM to circumvent cell wall damage by triggering adaptations that are complex but completely different from that of the cell wall stress stimulon. In summary, these results reveal phenotypic changes and transcriptome adaptations in a unique pbpB mutant and provide evidence to support the idea that exogenous spermine may perturb normal cell wall formation through its interactions with PBP 2.

Dataset Information

Penicillin Binding Protein 1 Is Important in the Compensatory Response of Staphylococcus aureus to Daptomycin-Induced Membrane Damage and Is a Potential Target for ?-Lactam-Daptomycin Synergy.

Publications

Penicillin Binding Protein 1 Is Important in the Compensatory Response of Staphylococcus aureus to Daptomycin-Induced Membrane Damage and Is a Potential Target for β-Lactam-Daptomycin Synergy.

Similar Datasets

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