Biochemical and functional characterization of UDP-galactose 4-epimerase from Aeromonas hydrophila

Shivani Agarwal, Keshav Gopal, Tanuja Upadhyaya, Aparna Dixit*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Bacteria of genus Aeromonas, responsible for a variety of pathological conditions in humans and fish, are ubiquitous waterborne bacteria. Aeromonas produces several virulent factors including a complex of lipopolysaccharide and surface array protein, involved in colonization. UDP-galactose 4-epimerase (GalE) catalyzes the production of UDP-galactose, a precursor for lipopolysaccharide biosynthesis, and thus is an important drug target. GalE exhibits interspecies variation and heterogeneity at its structural and functional level and therefore, the differences between the GalE of the host and the pathogen can be exploited for drug designing. In the present study, we report biochemical and functional characterization of the recombinant GalE of Aeromonas hydrophila. Unlike GalE reported from all other species, the purified recombinant GalE of A. hydrophila was found to exist as a monomer. This is the first report of UDP-galactose 4-epimerase from any species being a monomer. The molecular mass of the 6×His-rGalE was determined to be 38271.477 (m/z). The 6×His-rGalE with a Km of 0.5 mM for UDP-galactose exhibited optimum activity at 37 °C and pH 8-9. Spectrofluorimetric and CD analysis confirmed that the thermal inactivation was due to structural changes and not due to the NAD-dissociation. A relatively more ordered structure of the enzyme at pH 8 and 9 as compared to that at pH 6 or 7 suggests a key role of the electrostatic interactions in maintaining its native tertiary structure.

Original languageEnglish (US)
Pages (from-to)828-837
Number of pages10
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number7
StatePublished - Jul 2007


  • Aeromonas hydrophila
  • Circular dichroism
  • Fluorescence spectroscopy
  • UDP-galactose 4-epimerase

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology


Dive into the research topics of 'Biochemical and functional characterization of UDP-galactose 4-epimerase from Aeromonas hydrophila'. Together they form a unique fingerprint.

Cite this