Galactaro δ-lactone isomerase: lactone isomerization by a member of the amidohydrolase superfamily

Biochemistry. 2014 Feb 4;53(4):614-6. doi: 10.1021/bi5000492. Epub 2014 Jan 24.


Agrobacterium tumefaciens strain C58 can utilize d-galacturonate as a sole source of carbon via a pathway in which the first step is oxidation of d-galacturonate to D-galactaro-1,5-lactone. We have identified a novel enzyme, D-galactarolactone isomerase (GLI), that catalyzes the isomerizaton of D-galactaro-1,5-lactone to D-galactaro-1,4-lactone. GLI, a member of the functionally diverse amidohydrolase superfamily, is a homologue of LigI that catalyzes the hydrolysis of 2-pyrone-4,6-dicarboxylate in lignin degradation. The ability of GLI to catalyze lactone isomerization instead of hydrolysis can be explained by the absence of the general basic catalysis used by 2-pyrone-4,6-dicarboxylate lactonase.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Agrobacterium tumefaciens / enzymology*
  • Amidohydrolases / chemistry*
  • Bacterial Proteins / chemistry*
  • Isomerases / chemistry*
  • Isomerism
  • Lactones / chemistry*
  • Models, Molecular
  • Protein Conformation


  • Bacterial Proteins
  • Lactones
  • Amidohydrolases
  • Isomerases

Associated data

  • PDB/4MUP