1UKO

Crystal structure of soybean beta-amylase mutant substituted at surface region

Summary for 1UKO

• Entry DOI: 10.2210/pdb1uko/pdb
• Related: 1BFN 1BYA 1BYB 1BYC 1BYD 1FA2 1UKP
• Descriptor: Beta-amylase, SULFATE ION (3 entities in total)
• Functional Keywords: (alpha/beta)8 barrel, hydrolase
• Biological source: Glycine max (soybean)
• Total number of polymer chains: 4
• Total formula weight: 226606.59

Authors

Kang, Y.N.,Adachi, M.,Mikami, B.,Utsumi, S. (deposition date: 2003-08-30, release date: 2004-02-10, Last modification date: 2023-10-25)

Primary citation

Kang, Y.N.,Adachi, M.,Mikami, B.,Utsumi, S.
Change in the crystal packing of soybean beta-amylase mutants substituted at a few surface amino acid residues
Protein Eng., 16:809-817, 2003

PubMed Abstract: 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.

PubMed: 14631070
DOI: 10.1093/protein/gzg109

Experimental method

X-RAY DIFFRACTION (2.1 Å)