Native Electrophoresis-Coupled Activity Assays Reveal Catalytically-Active Protein Aggregates of Escherichia coli β-Glucuronidase

PLoS One. 2015 Jun 29;10(6):e0130269. doi: 10.1371/journal.pone.0130269. eCollection 2015.

Abstract

β-glucuronidase is found as a functional homotetramer in a variety of organisms, including humans and other animals, as well as a number of bacteria. This enzyme is important in these organisms, catalyzing the hydrolytic removal of a glucuronide moiety from substrate molecules. This process serves to break down sugar conjugates in animals and provide sugars for metabolism in bacteria. While β-glucuronidase is primarily found as a homotetramer, previous studies have indicated that the human form of the protein is also catalytically active as a dimer. Here we present evidence for not only an active dimer of the E. coli form of the protein, but also for several larger active complexes, including an octomer and a 16-mer. Additionally, we propose a model for the structures of these large complexes, based on computationally-derived molecular modeling studies. These structures may have application in the study of human disease, as several diseases have been associated with the aggregation of proteins.

MeSH terms

  • Bacterial Proteins / chemistry*
  • Carbohydrates / chemistry
  • Catalysis
  • Catalytic Domain
  • Computer Simulation
  • Dimerization
  • Electrophoresis, Polyacrylamide Gel / methods*
  • Escherichia coli / enzymology*
  • Glucuronidase / chemistry*
  • Glucuronides / chemistry
  • Humans
  • Hydrolysis
  • Kinetics
  • Models, Molecular
  • Protein Aggregates
  • Protein Binding
  • Protein Conformation
  • Protein Folding

Substances

  • Bacterial Proteins
  • Carbohydrates
  • Glucuronides
  • Protein Aggregates
  • Glucuronidase

Grants and funding

The authors received no external funding for this work.