Identification of acceptor substrate binding subsites +2 +3 in the amylomaltase from Thermus thermophilus HB8

Glycoside hydrolase family 77 (GH77) belongs to the α-amylase superfamily (Clan H) together with GH13 and GH70. GH77 enzymes are amylomaltases or 4-α-glucanotransferases, involved in maltose metabolism in microorganisms and in starch biosynthesis in plants. Here we characterized the amylomaltase from the hyperthermophilic bacterium Thermus...

Two novel, putatively cell wall-associated and glycosylphosphatidylinositol-anchored α-glucanotransferase enzymes of Aspergillus niger

In the genome sequence of Aspergillus niger CBS 513.88, three genes were identified with high similarity to fungal α-amylases. The protein sequences derived from these genes were different in two ways from all described fungal α-amylases: they were predicted to be glycosylphosphatidylinositol anchored, and some highly conserved amino acids of...

Three-way stabilization of the covalent intermediate in amylomaltase, an alpha-like transglycosylase

Amylomaltases are glycosyl hydrolases belonging to glycoside hydrolase family 77 that are capable of the synthesis of large cyclic glucans and the disproportionation of oligosaccharides. Using protein crystallography, we have generated a flip book movie of the amylomaltase catalytic cycle in atomic detail. The structures include a covalent...

Amylomaltase of Pyrobaculum aerophilum IM2 produces thermoreversible starch gels

Amylomaltases are 4-alpha-glucanotransferases (EC 2.4.1.25) of glycoside hydrolase family 77 that transfer alpha-1,4-linked glucans to another acceptor, which can be the 4-OH group of an alpha-1,4-linked glucan or glucose. The amylomaltase-encoding gene (PAE1209) from the hyperthermophilic archaeon Pyrobaculum aerophilum IM2 was cloned and...