Amylomaltase MalQ is essential for the metabolism of maltose and maltodextrins in Escherichia coli. It catalyzes transglycosylation/disproportionation reactions in which glycosyl or dextrinyl units are transferred among linear maltodextrins of various lengths [2]. This domain called N2 resembles a beta-sandwich consisting of a five-stranded mixed beta-sheet and a short two-stranded antiparallel beta-sheet. The N2 structure is reminiscent of carbohydrate-binding modules (CBMs) [2]. However, a comparison with structurally known CBMs did not reveal significant similarities.

1: Group B streptococcus pullulanase crystal structures in the context of a novel strategy for vaccine development. Gourlay LJ, Santi I, Pezzicoli A, Grandi G, Soriani M, Bolognesi M; J Bacteriol. 2009;191:3544-3552. PMID:19329633

2: Structural Basis for the Interconversion of Maltodextrins by MalQ, the Amylomaltase of Escherichia coli. Weiss SC, Skerra A, Schiefner A; J Biol Chem. 2015;290:21352-21364. PMID:26139606

3: Crystal Structure of Amylomaltase from Corynebacterium glutamicum. Joo S, Kim S, Seo H, Kim KJ; J Agric Food Chem. 2016;64:5662-5670. PMID:27366969