Characterization of a novel Agrobacterium tumefaciens galactarolactone cycloisomerase enzyme for direct conversion of D-galactarolactone to 3-deoxy-2-keto-L-threo-hexarate.

ABSTRACT: Microorganisms use different pathways for D-galacturonate catabolism. In the known microbial oxidative pathway, D-galacturonate is oxidized to D-galactarolactone, the lactone hydrolyzed to galactarate, which is further converted to 3-deoxy-2-keto-hexarate and α-ketoglutarate. We have shown recently that Agrobacterium tumefaciens strain C58 contains an uronate dehydrogenase (At Udh) that oxidizes D-galacturonic acid to D-galactarolactone. Here we report identification of a novel enzyme from the same A. tumefaciens strain, which we named Galactarolactone cycloisomerase (At Gci) (E.C. 5.5.1.-), for the direct conversion of the D-galactarolactone to 3-deoxy-2-keto-hexarate. The At Gci enzyme is 378 amino acids long and belongs to the mandelate racemase subgroup in the enolase superfamily. At G

SUBMITTER: Andberg M 

PROVIDER: S-EPMC3366811 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature