Crystal structure analysis of a bacterial aryl acylamidase belonging to the amidase signature enzyme family

Saeyoung Lee, Eun Hye Park, Hyeok Jin Ko, Won Gi Bang, Hye Yeon Kim, Kyoung Heon Kim, In Geol Choi

Research output: Contribution to journalArticle

11 Citations (Scopus)

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 languageEnglish
Pages (from-to)268-274
Number of pages7
JournalBiochemical and biophysical research communications
Volume467
Issue number2
DOIs
Publication statusPublished - 2015 Nov 13

Keywords

  • Amidase signature enzyme family
  • Aryl acylamidase
  • Ser-cisSer-Lys catalytic triad
  • p-acetaminophenol

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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