Unsaturated glucuronyl hydrolase of Bacillus sp GL1: Novel enzyme prerequisite for metabolism of unsaturated oligosaccharides produced by polysaccharide lyases

The bacterium Bacillus sp, GL1 assimilates two kinds of heteropolysaccharid es, gellan and xanthan, by using extracellular gellan and xanthan lyases, r espectively, and produces unsaturated saccharides as the first degradation products. A novel unsaturated glucuronyl hydrolase (glycuronidase), which w as induced in the bacterial cells grown on either gellan or xanthan, was fo und to act on the tetrasaccharide of unsaturated glucuronyl-glucosyl-rhamno syl-glucose produced from gellan by gellan lyase, and the enzyme and its ge ne were isolated from gellan-grown cells. The nucleotide sequence showed th at the gene contained an ORF consisting of 1131 base pairs coding a polypep tide with a molecular weight of 42,859, The purified enzyme was a monomer w ith a molecular mass of 12 kDa and was most active at pH 6.0 and 45 degrees C, Because the enzyme can act not only on the gellan-degrading product by gellan lyase, but also on unsaturated - chondroitin and hyaluronate disacch arides produced by chondroitin and hyaluronate lyases, respectively, it is considered that the unsaturated glucuronyl hydrolase plays specific and ubi quitous roles in the degradation of oligosaccharides with unsaturated uroni c acid at the nonreducing terminal produced by polysaccharide lyases. (C) 1 999 Academic Press.