2g3n
Crystal structure of the Sulfolobus solfataricus alpha-glucosidase MalA in complex with beta-octyl-glucopyranoside
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OverviewOverview
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.
About this StructureAbout this Structure
2G3N is a Single protein structure of sequence from Sulfolobus solfataricus with BOG as ligand. Active as Alpha-glucosidase, with EC number 3.2.1.20 Full crystallographic information is available from OCA.
ReferenceReference
Structure of the Sulfolobus solfataricus alpha-glucosidase: implications for domain conservation and substrate recognition in GH31., Ernst HA, Lo Leggio L, Willemoes M, Leonard G, Blum P, Larsen S, J Mol Biol. 2006 May 12;358(4):1106-24. Epub 2006 Mar 13. PMID:16580018
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