A Computational Evaluation of the Mechanism of Penicillin-Binding Protein-Catalyzed Cross-Linking of the Bacterial Cell Wall
- 18 March 2011
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 133 (14), 5274-5283
- https://doi.org/10.1021/ja1074739
Abstract
Penicillin-binding protein 1b (PBP 1b) of the Gram-positive bacterium Streptococcus pneumoniae catalyzes the cross-linking of adjacent peptidoglycan strands, as a critical event in the biosynthesis of its cell wall. This enzyme is representative of the biosynthetic PBP structures of the β-lactam-recognizing enzyme superfamily and is the target of the β-lactam antibiotics. In the cross-linking reaction, the amide between the -d-Ala-d-Ala dipeptide at the terminus of a peptide stem acts as an acyl donor toward the ε-amino group of a lysine found on an adjacent stem. The mechanism of this transpeptidation was evaluated using explicit-solvent molecular dynamics simulations and ONIOM quantum mechanics/molecular mechanics calculations. Sequential acyl transfer occurs to, and then from, the active site serine. The resulting cross-link is predicted to have a cis-amide configuration. The ensuing and energetically favorable cis- to trans-amide isomerization, within the active site, may represent the key event driving product release to complete enzymatic turnover.This publication has 44 references indexed in Scilit:
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