| Autor: |
Brendan R. Amer, J. Andrew McCammon, Michael E. Jung, Robert T. Clubb, Sung Wook Yi, Grace L. Huang, Alex W. Jacobitz, Angelyn V. Nguyen, Jeff Wereszczynski, Michael R. Sawaya |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Biophysical Journal. 106:677a |
| ISSN: |
0006-3495 |
| Popis: |
Sortase cysteine transpeptidases covalently attach proteins to the bacterial cell wall or assemble fiber-like pili that promote bacterial adhesion. Members of this enzyme superfamily are widely distributed in Gram-positive bacteria which frequently utilize multiple sortases to elaborate their peptidoglycan. Sortases catalyze transpeptidation using a conserved active site His-Cys-Arg triad that joins a sorting signal located at the C-terminus of their protein substrate to an amino nucleophile located on the cell surface. In order to understand the molecular basis of substrate recognition, we solved a crystal structure of the Staphylococcus aureus Sortase B enzyme (SrtB) in a covalent complex with an analog of its NPQTN sorting signal substrate. The results of computational modeling, molecular dynamics (MD) simulations, and targeted amino acid mutagenesis indicate that the backbone amide of Glu224 and the side chain of Arg233 form an oxyanion hole in SrtB which stabilizes high-energy catalytic intermediates. Surprisingly, a highly conserved threonine residue within the bound sorting signal substrate facilitates construction of the oxyanion hole by stabilizing the position of the active site arginine residue via hydrogen bonding. MD simulations and primary sequence conservation suggest that the sorting signal-stabilized oxyanion hole is a universal feature of enzymes within the sortase superfamily. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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