Polypeptide folding of Bacillus cereus ATCC7064 oligo-1,6-glucosidase revealed by 3.0 A resolution X-ray analysis

• Published in: Journal of biochemistry (Tokyo) Vol. 113; no. 6; p. 646
• Main Authors: Kizaki, H, Hata, Y, Watanabe, K, Katsube, Y, Suzuki, Y
• Format: Journal Article
• Language: English
• Published: England 01-06-1993
• Subjects: Bacillus cereus - enzymology; Molecular Structure; Oligo-1,6-Glucosidase - chemistry; Protein Folding; Protein Structure, Secondary; X-Ray Diffraction
• ISSN: 0021-924X
• DOI: 10.1093/oxfordjournals.jbchem.a124097

The crystal structure of an oligo-1,6-glucosidase from Bacillus cereus ATCC7064 was determined by the X-ray diffraction method at 3.0 A resolution. The structure was solved by the multiple isomorphous replacement method and refined to a crystallographic R-factor of 0.208, using the molecular dynamics refinement program, X-PLOR. The electron density map revealed the folding of a polypeptide chain consisting of 558 amino acid residues. The molecule can be subdivided into three domains (N-terminal domain, subdomain, and C-terminal domain). The N-terminal domain has an (alpha/beta)8-barrel structure called the TIM-barrel structure. The C-terminal domain is characterized by a beta-barrel structure composed of eight antiparallel beta-strands, while the subdomain has a loop-rich structure with a small alpha-helix and a beta-sheet. The enzyme has a large cleft between the N-terminal domain and the subdomain. The cleft leads from the molecular surface to the molecular center. The bottom of the cleft is at the C-terminal end of the parallel beta-strands of the (alpha/beta)8-barrel. These structural features closely resemble those of alpha-amylases from Aspergillus oryzae and pig pancreas.