title: Structure of Bacillus amyloliquefaciens alpha-amylase at high resolution: implications for thermal stability.
abstract: The crystal structure of Bacillus amyloliquefaciens alpha-amylase (BAA) at 1.4 A resolution revealed ambiguities in the thermal adaptation of homologous proteins in this family. The final model of BAA is composed of two molecules in a back-to-back orientation, which is likely to be a consequence of crystal packing. Despite a high degree of identity, comparison of the structure of BAA with those of other liquefying-type alpha-amylases indicated moderate discrepancies at the secondary-structural level. Moreover, a domain-displacement survey using anisotropic B-factor and domain-motion analyses implied a significant contribution of domain B to the total flexibility of BAA, while visual inspection of the structure superimposed with that of B. licheniformis alpha-amylase (BLA) indicated higher flexibility of the latter in the central domain A. Therefore, it is suggested that domain B may play an important role in liquefying alpha-amylases, as its rigidity offers a substantial improvement in thermostability in BLA compared with BAA.
authors.affiliation: Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan. khajeh@modares.ac.ir
authors.forename: Jahan
authors.initials: J
authors.lastname: Alikhajeh
authors.forename: Khosro
authors.initials: K
authors.lastname: Khajeh
authors.forename: Bijan
authors.initials: B
authors.lastname: Ranjbar
authors.forename: Hossein
authors.initials: H
authors.lastname: Naderi-Manesh
authors.forename: Yi Hung
authors.initials: YH
authors.lastname: Lin
authors.forename: Enhung
authors.initials: E
authors.lastname: Liu
authors.forename: Hong Hsiang
authors.initials: HH
authors.lastname: Guan
authors.forename: Yin Cheng
authors.initials: YC
authors.lastname: Hsieh
authors.forename: Phimonphan
authors.initials: P
authors.lastname: Chuankhayan
authors.forename: Yen Chieh
authors.initials: YC
authors.lastname: Huang
authors.forename: Jeyakanthan
authors.initials: J
authors.lastname: Jeyaraman
authors.forename: Ming Yih
authors.initials: MY
authors.lastname: Liu
authors.forename: Chun Jung
authors.initials: CJ
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D055672:Static Electricity; D040681:Structural Homology, Protein; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000516:alpha-Amylases