1B90

BACILLUS CEREUS BETA-AMYLASE APO FORM

Summary for 1B90

• Entry DOI: 10.2210/pdb1b90/pdb
• Descriptor: PROTEIN (BETA-AMYLASE), ACETATE ION, SULFATE ION, ... (5 entities in total)
• Functional Keywords: hydrolase(o-glycosyl), hydrolase
• Biological source: Bacillus cereus
• Total number of polymer chains: 1
• Total formula weight: 58553.71

Authors

Mikami, B.,Adachi, M.,Kage, T.,Sarikaya, E.,Nanmori, T.,Shinke, R.,Utsumi, S. (deposition date: 1999-03-06, release date: 1999-03-15, Last modification date: 2024-11-13)

Primary citation

Mikami, B.,Adachi, M.,Kage, T.,Sarikaya, E.,Nanmori, T.,Shinke, R.,Utsumi, S.
Structure of raw starch-digesting Bacillus cereus beta-amylase complexed with maltose.
Biochemistry, 38:7050-7061, 1999

PubMed Abstract: The crystals of beta-amylase from Bacillus cereus belong to space group P21 with the following cell dimensions: a = 57.70 A, b = 92.87 A, c = 65.93 A, and beta =101.95 degrees. The structures of free and maltose-bound beta-amylases were determined by X-ray crystallography at 2.1 and 2.5 A with R-factors of 0.170 and 0.164, respectively. The final model of the maltose-bound form comprises 516 amino acid residues, four maltose molecules, 275 water molecules, one Ca2+, one acetate, and one sulfate ion. The enzyme consists of a core (beta/alpha)8-barrel domain (residues 5-434) and a C-terminal starch-binding domain (residues 435-613). Besides the active site in the core where two maltose molecules are bound in tandem, two novel maltose-binding sites were found in the core L4 region and in the C-terminal domain. The structure of the core domain is similar to that of soybean beta-amylase except for the L4 maltose-binding site, whereas the C-terminal domain has the same secondary structure as domain E of cyclodextrin glucosyltransferase. These two maltose-binding sites are 32-36 A apart from the active site. These results indicate that the ability of B. cereus beta-amylase to digest raw starch can be attributed to the additional two maltose-binding sites.

PubMed: 10353816
DOI: 10.1021/bi9829377

Experimental method

X-RAY DIFFRACTION (2.5 Å)