Abstract
The atomic structure of a bacterial aryl acylamidase (EC 3.5.1.13; AAA) is reported and structural features are investigated to better understand the catalytic profile of this enzyme. Structures of AAA were determined in its native form and in complex with the analgesic acetanilide, p-acetaminophenol, at 1.70 Å and 1.73 Å resolutions, respectively. The overall structural fold of AAA was identified as an α/β fold class, exhibiting an open twisted β-sheet core surrounded by α-helices. The asymmetric unit contains one AAA molecule and the monomeric form is functionally active. The core structure enclosing the signature sequence region, including the canonical Ser-cisSer-Lys catalytic triad, is conserved in all members of the Amidase Signature enzyme family. The structure of AAA in a complex with its ligand reveals a unique organization in the substrate-binding pocket. The binding pocket consists of two loops (loop1 and loop2) in the amidase signature sequence and one helix (α10) in the non-amidase signature sequence. We identified two residues (Tyr136 and Thr330) that interact with the ligand via water molecules, and a hydrogen-bonding network that explains the catalytic affinity over various aryl acyl compounds. The optimum activity of AAA at pH > 10 suggests that the reaction mechanism employs Lys84 as the catalytic base to polarize the Ser187 nucleophile in the catalytic triad.
Original language | English |
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Pages (from-to) | 268-274 |
Number of pages | 7 |
Journal | Biochemical and biophysical research communications |
Volume | 467 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2015 Nov 13 |
Bibliographical note
Funding Information:This work is supported by a Korea University grant. We thank the beamline (PLS 5C) staff at Pohang Light Source for technical support during data collection.
Publisher Copyright:
© 2015 Elsevier Inc. All rights reserved.
Keywords
- Amidase signature enzyme family
- Aryl acylamidase
- Ser-cisSer-Lys catalytic triad
- p-acetaminophenol
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Molecular Biology
- Cell Biology