Early Insights into the Interactions of Different β-Lactam Antibiotics and β-Lactamase Inhibitors against Soluble Forms of Acinetobacter baumannii PBP1a and Acinetobacter sp. PBP3

Papp-Wallace, Krisztina M.; Senkfor, Baui; Gatta, Julian A.; Chai, Weirui; Taracila, Magdalena A.; Shanmugasundaram, Veerabahu; Han, Seungil; Zaniewski, Richard P.; Lacey, Brian M.; Tomaras, Andrew P.; Skalweit, Marion J.; Harris, Michael E.; Rice, Louis B.; Buynak, John D.; Bonomo, Robert A.

doi:10.1128/aac.01027-12

Cited by 33 publications

(30 citation statements)

References 50 publications

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“…It was first suggested that the mechanism of the antibacterial activity of sulbactam against A. baumannii was primarily via inhibition of PBP1a and PBP2 (17). Although it has been reported that sulbactam preferentially binds PBP3 over PBP1a, with 50% inhibitory concentration (IC 50 ) values of 4 M and 55 M, respectively (18), with a mode of binding to the active site similar to that of ampicillin (18), no evaluation of the binding affinity for PBP2 was made in that study. Therefore, to understand the relative affinity of sulbactam for PBP2 versus PBP1 orthologs or PBP3, membranes containing these proteins were purified from an A. baumannii clinical isolate, ATCC 17978, and subjected to a standard gel-based Bocillin FL competition assay (37).…”

Section: Resultsmentioning

confidence: 90%

“…As shown in Table 4, sulbactam resistance at 4ϫ MIC mapped to pbp3 in both strain backgrounds, resulting in a serine-to-threonine substitution at position 390 in the resistant ATCC 17978 mutant and a serine-to-phenylalanine substitution at position 395 in one of the resistant ARC2058 mutants. Both of these mutations are at or near the sulbactam binding site of PBP3 (18). The resistant ARC2058 pbp3 mutant strain also had a frameshift mutation in a hypothetical protein that has similarity to a protein that belongs to the peptidase C13 family.…”

Section: Resultsmentioning

confidence: 99%

“…(17). Preliminary in vitro experiments have demonstrated that sulbactam binds to penicillin-binding proteins (PBPs) of Acinetobacter spp., and it is presumed that this activity is responsible for the observed bacterial killing (18,19). Although historically ampicillin-sulbactam has been effective in treating VAP, bacteremia, and other nosocomial infections caused by A. baumannii (20)(21)(22)(23), clinical resistance is emerging (24).…”

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confidence: 99%

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Molecular Mechanisms of Sulbactam Antibacterial Activity and Resistance Determinants in Acinetobacter baumannii

Penwell

Shapiro

Giacobbe

et al. 2015

Antimicrob Agents Chemother

173

136

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Sulbactam is a class A ␤-lactamase inhibitor with intrinsic whole-cell activity against certain bacterial species, including Acinetobacter baumannii. The clinical use of sulbactam for A. baumannii infections is of interest due to increasing multidrug resistance in this pathogen. However, the molecular drivers of its antibacterial activity and resistance determinants have yet to be precisely defined. Here we show that the antibacterial activities of sulbactam vary widely across contemporary A. baumannii clinical isolates and are mediated through inhibition of the penicillin-binding proteins (PBPs) PBP1 and PBP3, with very low frequency of resistance; the rare pbp3 mutants with high levels of resistance to sulbactam are attenuated in fitness. These results support further investigation of the potential clinical utility of sulbactam.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular Mechanisms of Sulbactam Antibacterial Activity and Resistance Determinants in Acinetobacter baumannii

Penwell

Shapiro

Giacobbe

et al. 2015

Antimicrob Agents Chemother

173

136

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“…The PBP enzymes are a significant component of Gram-positive ␤-lactam resistance and are emerging as a source of Gramnegative resistance in bacteria such as Acinetobacter baumannii (64). Our studies of Pa sPBP5 provide a detailed analysis of its dual DD-carboxypeptidase and ␤-lactamase activities and suggest the structural basis for its remarkable ability to hydrolyze carbapenems.…”

Section: Discussionmentioning

confidence: 99%

Structural Analysis of the Role of Pseudomonas aeruginosa Penicillin-Binding Protein 5 in β-Lactam Resistance

Smith

Kumarasiri

Zhang

et al. 2013

Antimicrob Agents Chemother

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b Penicillin-binding protein 5 (PBP5) is one of the most abundant PBPs in Pseudomonas aeruginosa. Although its main function is that of a cell wall DD-carboxypeptidase, it possesses sufficient ␤-lactamase activity to contribute to the ability of P. aeruginosa to resist the antibiotic activity of the ␤-lactams. The study of these dual activities is important for understanding the mechanisms of antibiotic resistance by P. aeruginosa, an important human pathogen, and to the understanding of the evolution of ␤-lactamase activity from the PBP enzymes. We purified a soluble version of P. aeruginosa PBP5 (designated Pa sPBP5) by deletion of its C-terminal membrane anchor. Under in vitro conditions, Pa sPBP5 demonstrates both DD-carboxypeptidase and expanded-spectrum ␤-lactamase activities. Its crystal structure at a 2.05-Å resolution shows features closely resembling those of the class A ␤-lactamases, including a shortened loop spanning residues 74 to 78 near the active site and with respect to the conformations adopted by two active-site residues, Ser101 and Lys203. These features are absent in the related PBP5 of Escherichia coli. A comparison of the two Pa sPBP5 monomers in the asymmetric unit, together with molecular dynamics simulations, revealed an active-site flexibility that may explain its carbapenemase activity, a function that is absent in the E. coli PBP5 enzyme. Our functional and structural characterizations underscore the versatility of this PBP5 in contributing to the ␤-lactam resistance of P. aeruginosa while highlighting how broader ␤-lactamase activity may be encoded in the structural folds shared by the PBP and serine ␤-lactamase classes.

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“…Recent evidence suggests that low inhibitory concentrations of ampicillin/sulbactam for PBP3 may contribute to the effectiveness of this combination against A. baumannii [157]. Nevertheless, increasing rates of bacterial resistance of A.…”

Section: Microbiologymentioning

confidence: 99%

Improving antimicrobial use in critically ill patients

Adnan¹

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Early Insights into the Interactions of Different β-Lactam Antibiotics and β-Lactamase Inhibitors against Soluble Forms of Acinetobacter baumannii PBP1a and Acinetobacter sp. PBP3

Cited by 33 publications

References 50 publications

Molecular Mechanisms of Sulbactam Antibacterial Activity and Resistance Determinants in Acinetobacter baumannii

Molecular Mechanisms of Sulbactam Antibacterial Activity and Resistance Determinants in Acinetobacter baumannii

Structural Analysis of the Role of Pseudomonas aeruginosa Penicillin-Binding Protein 5 in β-Lactam Resistance

Improving antimicrobial use in critically ill patients

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