1uko
Crystal structure of soybean beta-amylase mutant substituted at surface region
|
OverviewOverview
In spite of the high similarity of amino acid sequence and, three-dimensional structure between soybean beta-amylase (SBA) and sweet, potato beta-amylase (SPB), their quaternary structure is quite different, being a monomer in SBA and a tetramer in SPB. Because most of the, differences in amino acid sequences are found in the surface region, we, tested the tetramerization of SBA by examining mutations of residues, located at the surface. We designed the SBA tetramer using the SPB, tetramer structure as a model and calculating the change of accessible, surface area (DeltaASA) for each residue in order to select sites for the, mutation. Two different mutant genes encoding SB3 (D374Y/L481R/P487D) and, SB4 (K462S added to SB3), were constructed for expression in Escherichia, coli and the recombinant proteins were purified. They existed as a monomer, in solution, but gave completely different crystals from the native SBA., The asymmetric unit of the mutants contains four molecules, while that of, native SBA contains one. The interactions of the created interfaces, revealed that there were more intermolecular interactions in the SB3 than, in the SB4 tetramer. The substituted charged residues on the surface are, involved in interactions with adjacent molecules in a different way, forming a new crystal packing pattern.
About this StructureAbout this Structure
1UKO is a Single protein structure of sequence from Glycine max with SO4 as ligand. Active as Beta-amylase, with EC number 3.2.1.2 Full crystallographic information is available from OCA.
ReferenceReference
Change in the crystal packing of soybean beta-amylase mutants substituted at a few surface amino acid residues., Kang YN, Adachi M, Mikami B, Utsumi S, Protein Eng. 2003 Nov;16(11):809-17. PMID:14631070
Page seeded by OCA on Wed Nov 21 04:11:57 2007