baumannii to sulbactam and is the most common carbapenem-resistance determinant in A. Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340, USA. The bla OXA-23 gene encodes a carbapenem-hydrolysing class D -lactamase known to reduce susceptibility of A. aeruginosa PBP3 and open avenues for future design of inhibitors of this class of PBPs. Taken together, these structural, biochemical, and computational studies provide a molecular basis for recognition of P. Energetic analysis of tightly and loosely held computed hydration sites indicates protein desolvation effects contribute significantly to PBP3 binding, and analysis of hydration site energies allows rank ordering of the second-order acylation rate constants. This is also the first example of a siderophore-conjugated triazolone-linked monocarbam complexed with any PBP. The model shows a different orientation of its two domains compared to earlier models of other class B PBPs and a novel, larger N-domain. Importantly, we have identified a novel conformation that is distinct to the high-molecular-weight class B PBP subfamily, which is identifiable by common features such as a hydrophobic aromatic wall formed by Tyr503, Tyr532, and Phe533 and the structural flexibility of Tyr409 flanked by two glycine residues. PBP3 is a class B PBP, possessing an N-terminal non-penicillinbinding domain, sometimes called a dimerization domain, and a C-terminal transpeptidase domain. The structure of MC-1, a new siderophore-conjugated monocarbam complexed with PBP3 provides molecular insights for lead optimization. aeruginosa PBP3 is due to a distinct hydrophobic aromatic wall composed of Tyr503, Tyr532, and Phe533 interacting with the gem-dimethyl group. The well-known affinity of the monobactam aztreonam for P. These structures reveal a conformational rearrangement of Tyr532 and Phe533 and a ligand-induced conformational change of Tyr409 and Arg489. aeruginosa PBP3 with both novel and marketed β-lactams. Here we disclose the first high resolution cocrystal structures of the P. Penicillin-binding protein PBP3, a key therapeutic target, is an essential enzyme responsible for the final steps of peptidoglycan synthesis and is covalently inactivated by β-lactam antibiotics. It might play an important role in the positioning of these proteins within the divisome.Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that causes nosocomial infections for which there are limited treatment options. The periplasmic loop 9/10 of FtsW appeared to be involved in the interaction with both PBP1B and PBP3. However, it could not be detected in the immunoprecipitated FtsW-PBP3 complex. By using a two-hybrid assay, the class A PBP1B was shown to interact with FtsW. The K2-V42 peptide of PBP3 containing the membrane-spanning sequence is a structural determinant sufficient for interaction with FtsW and for PBP3 dimerization. These proteins are able to form a discrete complex independently of the other cell-division proteins. In this work we show direct interactions between FtsW and PBP3 in vivo and in vitro by FRET (Förster resonance energy transfer) and co-immunoprecipitation experiments.
It requires the putative lipid II flippase FtsW for its localization at the division site and is necessary for the midcell localization of the class A PBP1B. In Escherichia coli, the class B PBP3 is specific for septal peptidoglycan synthesis. The morphogenetic protein complex responsible for the septation during cell division (the divisome) includes class A and class B penicillin-binding proteins (PBPs). Nguyen-Distèche, M.ĭuring the cell cycle of rod-shaped bacteria, two morphogenetic processes can be discriminated: length growth of the cylindrical part of the cell and cell division by formation of two new cell poles. The integral membrane FtsW protein and peptidoglycan synthase PBP3 form a subcomplex in Escherichia coli
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