1bli
From Proteopedia
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[[Image:1bli.gif|left|200px]] | [[Image:1bli.gif|left|200px]] | ||
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'''BACILLUS LICHENIFORMIS ALPHA-AMYLASE''' | '''BACILLUS LICHENIFORMIS ALPHA-AMYLASE''' | ||
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[[Category: Machius, M.]] | [[Category: Machius, M.]] | ||
[[Category: Wiegand, G.]] | [[Category: Wiegand, G.]] | ||
| - | [[Category: | + | [[Category: Alpha-1,4-glucan-4-glucanohydrolase]] |
| - | [[Category: | + | [[Category: Alpha-amylase]] |
| - | [[Category: | + | [[Category: Calcium]] |
| - | [[Category: | + | [[Category: Glycosyltransferase]] |
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Sodium]] |
| - | [[Category: | + | [[Category: Starch degradation]] |
| - | [[Category: | + | [[Category: Thermostability]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:40:13 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 08:40, 2 May 2008
BACILLUS LICHENIFORMIS ALPHA-AMYLASE
Overview
BACKGROUND: The structural basis as to how metals regulate the functional state of a protein by altering or stabilizing its conformation has been characterized in relatively few cases because the metal-free form of the protein is often partially disordered and unsuitable for crystallographic analysis. This is not the case, however, for Bacillus licheniformis alpha-amylase (BLA) for which the structure of the metal-free form is available. BLA is a hyperthermostable enzyme which is widely used in biotechnology, for example in the breakdown of starch or as a component of detergents. The determination of the structure of BLA in the metal-containing form, together with comparisons to the apo enzyme, will help us to understand the way in which metal ions can regulate enzyme activity. RESULTS: We report here the crystal structure of native, metal-containing BLA. The structure shows that the calcium-binding site which is conserved in all alpha-amylases forms part of an unprecedented linear triadic metal array, with two calcium ions flanking a central sodium ion. A region around the metal triad comprising 21 residues exhibits a conformational change involving a helix unwinding and a disorder-->order transition compared to the structure of metal-free BLA. Another calcium ion, not previously observed in alpha-amylases, is located at the interface between domains A and C. CONCLUSIONS: We present a structural description of a major conformational rearrangement mediated by metal ions. The metal induced disorder-->order transition observed in BLA leads to the formation of the extended substrate-binding site and explains on a structural level the calcium dependency of alpha-amylases. Sequence comparisons indicate that the unique Ca-Na-Ca metal triad and the additional calcium ion located between domains A and C might be found exclusively in bacterial alpha-amylases which show increased thermostability. The information presented here may help in the rational design of mutants with enhanced performance in biotechnological applications.
About this Structure
1BLI is a Single protein structure of sequence from Bacillus licheniformis. Full crystallographic information is available from OCA.
Reference
Activation of Bacillus licheniformis alpha-amylase through a disorder-->order transition of the substrate-binding site mediated by a calcium-sodium-calcium metal triad., Machius M, Declerck N, Huber R, Wiegand G, Structure. 1998 Mar 15;6(3):281-92. PMID:9551551 Page seeded by OCA on Fri May 2 11:40:13 2008
