7VT9

CRYSTAL STRUCTURE AT 3.4 ANGSTROMS RESOLUTION OF Maltodextrin glucosidase, MalZ, FROM Escherichia coli

Summary for 7VT9

• Entry DOI: 10.2210/pdb7vt9/pdb
• Descriptor: Maltodextrin glucosidase (2 entities in total)
• Functional Keywords: alpha-amylase, maltodextrin glucosidase, hydrolase
• Biological source: Escherichia coli (strain K12)
• Total number of polymer chains: 2
• Total formula weight: 140812.39

Authors

Ahn, W.-C.,Ahn, Y.,Woo, E.-J. (deposition date: 2021-10-28, release date: 2022-10-26, Last modification date: 2023-11-29)

Primary citation

Ahn, W.C.,An, Y.,Song, K.M.,Park, K.H.,Lee, S.J.,Oh, B.H.,Park, J.T.,Woo, E.J.
Dimeric architecture of maltodextrin glucosidase (MalZ) provides insights into the substrate recognition and hydrolysis mechanism.
Biochem.Biophys.Res.Commun., 586:49-54, 2022

PubMed Abstract: Maltodextrin glucosidase (MalZ) is a key enzyme in the maltose utilization pathway in Escherichia coli that liberates glucose from the reducing end of the short malto-oligosaccharides. Unlike other enzymes in the GH13_21 subfamily, the hydrolytic activity of MalZ is limited to maltodextrin rather than long starch substrates, forming various transglycosylation products in α-1,3, α-1,4 or α-1,6 linkages. The mechanism for the substrate binding and hydrolysis of this enzyme is not well understood yet. Here, we present the dimeric crystal structure of MalZ, with the N-domain generating a unique substrate binding groove. The N-domain bears CBM34 architecture and forms a part of the active site in the catalytic domain of the adjacent molecule. The groove found between the N-domain and catalytic domain from the adjacent molecule, shapes active sites suitable for short malto-oligosaccharides, but hinders long stretches of oligosaccharides. The conserved residue of E44 protrudes at subsite +2, elucidating the hydrolysis pattern of the substrate by the glucose unit from the reducing end. The structural analysis provides a molecular basis for the substrate specificity and the enzymatic property, and has potential industrial application for protein engineering.

PubMed: 34826700
DOI: 10.1016/j.bbrc.2021.11.070

Experimental method

X-RAY DIFFRACTION (3.3 Å)