1bli
From Proteopedia
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==Overview== | ==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. ... | + | 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== | ==About this Structure== | ||
| - | 1BLI is a | + | 1BLI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_licheniformis Bacillus licheniformis] with CA and NA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] Structure known Active Sites: CA1, CA2, CA3, CS and NA1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BLI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: thermostability]] | [[Category: thermostability]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 15:01:38 2007'' |
Revision as of 12:56, 5 November 2007
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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 with CA and NA as ligands. Active as Alpha-amylase, with EC number 3.2.1.1 Structure known Active Sites: CA1, CA2, CA3, CS and NA1. 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
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