2G3N

Crystal structure of the Sulfolobus solfataricus alpha-glucosidase MalA in complex with beta-octyl-glucopyranoside

Summary for 2G3N

• Entry DOI: 10.2210/pdb2g3n/pdb
• Related: 2g3m
• Descriptor: Alpha-glucosidase, octyl beta-D-glucopyranoside (3 entities in total)
• Functional Keywords: hydrolase, alpha-glucosidase, enzyme-carbohydrate complex, glycoside hydrolase family 31, multidomain protein, (beta/alpha)8 barrel, retaining mechanism
• Biological source: Sulfolobus solfataricus
• Cellular location: Cytoplasm (By similarity): O59645
• Total number of polymer chains: 6
• Total formula weight: 485235.38

Authors

Ernst, H.A.,Lo Leggio, L.,Willemoes, M.,Leonard, G.,Blum, P.,Larsen, S. (deposition date: 2006-02-20, release date: 2006-05-02, Last modification date: 2023-08-30)

Primary citation

Ernst, H.A.,Lo Leggio, L.,Willemoes, M.,Leonard, G.,Blum, P.,Larsen, S.
Structure of the Sulfolobus solfataricus alpha-Glucosidase: Implications for Domain Conservation and Substrate Recognition in GH31.
J.Mol.Biol., 358:1106-1124, 2006

PubMed Abstract: The crystal structure of alpha-glucosidase MalA from Sulfolobus solfataricus has been determined at 2.5Angstrom resolution. It provides a structural model for enzymes representing the major specificity in glycoside hydrolase family 31 (GH31), including alpha-glucosidases from higher organisms, involved in glycogen degradation and glycoprotein processing. The structure of MalA shows clear differences from the only other structure known from GH31, alpha-xylosidase YicI. MalA and YicI share only 23% sequence identity. Although the two enzymes display a similar domain structure and both form hexamers, their structures differ significantly in quaternary organization: MalA is a dimer of trimers, YicI a trimer of dimers. MalA and YicI also differ in their substrate specificities, as shown by kinetic measurements on model chromogenic substrates. In addition, MalA has a clear preference for maltose (Glc-alpha1,4-Glc), whereas YicI prefers isoprimeverose (Xyl-alpha1,6-Glc). The structural origin of this difference occurs in the -1 subsite where MalA residues Asp251 and Trp284 could interact with OH6 of the substrate. The structure of MalA in complex with beta-octyl-glucopyranoside has been determined. It reveals Arg400, Asp87, Trp284, Met321 and Phe327 as invariant residues forming the +1 subsite in the GH31 alpha-glucosidases. Structural comparisons with other GH families suggest that the GH31 enzymes belong to clan GH-D.

PubMed: 16580018
DOI: 10.1016/j.jmb.2006.02.056

Experimental method

X-RAY DIFFRACTION (2.55 Å)