Vancomycin is a glycopeptide antibiotic used for the treatment of serious infections by Gram-positive pathogens. Vancomycin inhibits cell wall biosynthesis by targeting the d-Ala-d-Ala terminus of peptidoglycan (PG). The highly cross-linked heptapeptide aglycon structure of vancomycin is the d-Ala-d-Ala binding site. The first residue of vancomycin is N-methyl-leucine, which is crucial for the dipeptide binding. The removal of N-methyl-leucine by Edman degradation results in desleucyl-vancomycin devoid of antimicrobial activities. To investigate the function of N-methyl-leucine for the dipeptide binding in vancomycin, molecular dynamics simulations of vancomycin and three N-terminus-modified vancomycin derivatives: desleucyl-vancomycin, vancomycinNtoC, and vancomycinSar, binding to a PG unit of the sequence l-Ala-d-iso-Gln-l-Lys-d-Ala-d-Ala with an intact pentaglycine bridge structure attached to the bridge link of l-Lys were carried out. Glycopeptide-PG binding interactions were characterized by root-mean-square-deviation contour analysis of atomic positions in vancomycin and its three analogues bound to a PG unit. The overall sampling space for four glycopeptide-PG complexes shows four distinct distributions with a continuous change between the conformational spaces. The hydrogen bond analyses show that multiple hydrogen bonds between the d-Ala-d-Ala and the vancomycin aglycon structure strengthened the dipeptide binding. The simulations revealed that the removal or chemical modification of N-methyl-leucine significantly weakens the dipeptide binding to the aglycon structure and provides interesting structural insights into glycopeptide-PG binding interactions.
Pubmed ID: 29399648 RIS Download
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Software program that simulates molecular interactions. It has features that allow broad application to many-particle systems with a comprehensive set of energy functions, a variety of enhanced sampling methods, and support for multi-scale techniques, and a range of implicit solvent models. It also primarily targets biological systems including peptides, proteins, prosthetic groups, small molecule ligands, nucleic acids, lipids, and carbohydrates, as they occur in solution, crystals, and membrane environments. CHARMM can also be applied to inorganic materials with applications in materials design and has a comprehensive set of analysis and model builiding tools.
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