Novel glucoamylase-type enzymes from Thermoactinomyces vulgaris and Methanococcus jannaschii whose genes are found in the flanking region of the α-amylase genes

Abstract

A region downstream of the gene for pullulan-hydrolyzing alpha-amylase, TVA II, of Thermoactinomyces vulgaris R-47 was sequenced, and an open reading frame encoding an enzyme homologous to glucoamylase was found. The nucleotide sequence of this enzyme, designated TGA, consists of 1,953 base pairs corresponding to a protein of 651 amino acid residues. The TGA gene was subcloned and expressed in Escherichia coli. Enzymatic analyses showed that, like other glucoamylases, TGA produced beta-D-glucose from its substrate. However, TGA hydrolyzed maltooligosaccharides such as maltotetraose and maltose more efficiently than starch, while fungal glucoamylases preferred starch to maltooligosaccharides. The primary structure of TGA resembled a putative glucoamylase from the hyperthermophilic archaeon Methanococcus jannaschii (MGA), while homologies between TGA and the fungal glucoamylases were low. The enzymatic properties of recombinant MGA produced in E. coli cells were similar to those of TGA. These findings indicate that TGA and MGA are novel glucoamy-lase-type enzymes with oligosaccaharide-metabolizing activity.

Properties of a Novel Thermostable Glucoamylase from the Hyperthermophilic Archaeon Sulfolobus solfataricus in Relation to Starch Processing

“…However, the enzyme obviously liberated ␤-Dglucose from the substrate during the hydrolysis reaction, indicating that SSG can be distinguished from ␣-glucosidase, which releases ␣-D-glucose. Glucoamylases isolated from the hyperthermophilic archaea Methanococcus jannaschii and Thermoactinomyces vulgaris exhibited substrate specificity similar to that of SSG (23). Determination of the three-dimensional structures of these enzymes followed by comparison of their active sites with those of their fungal counterparts should explain the differences in the substrate specificity of these glucoamylases more clearly.…”

Cysteine Protease-Binding Protein Family 6 Mediates the Trafficking of Amylases to Phagosomes in the Enteric Protozoan Entamoeba histolytica

“…␥-Amylase (EHI_044370) has similarity with glucoamylase from Thermoactiomyces vulgaris (2 eϪ9), which has been shown to have high hydrolytic activity toward maltooligosaccharides (34). The substrates of ␣-amylase and ␥-amylase should be determined in the future to allow a better understanding of the biological and physiological roles of CPBF6.…”

Two Novel Glycoside Hydrolases Responsible for the Catabolism of Cyclobis-(1→6)-α-nigerosyl

“…Some bacterial glucoamylases, however, prefer maltooligosaccharides to soluble starch (14, 21, 22), and only two enzymes, glucodextranase (23) and ␣,␣-trehalase (24), are known to have different substrate specificities. The glucodextranase derived from A. globiformis I42 displays 100-and 19-fold higher activity for dextran and isomaltose, respectively, than for soluble starch (22). Kfla1896 and this glucodextranase have the same regioselectivity for ␣-1,6-glucosidic linkages but a different preference for the degree of polymerization of their substrates.…”