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==CRYSTAL STRUCTURE ANALYSIS OF THE MUTANT K300Q OF PSEUDOALTEROMONAS HALOPLANCTIS ALPHA-AMYLASE== | |||
<StructureSection load='1jd9' size='340' side='right'caption='[[1jd9]], [[Resolution|resolution]] 2.50Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[1jd9]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Pseudoalteromonas_haloplanktis Pseudoalteromonas haloplanktis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1JD9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1JD9 FirstGlance]. <br> | |||
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene></td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1jd9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1jd9 OCA], [https://pdbe.org/1jd9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1jd9 RCSB], [https://www.ebi.ac.uk/pdbsum/1jd9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1jd9 ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/AMY_PSEHA AMY_PSEHA] | |||
== Evolutionary Conservation == | |||
[[Image:Consurf_key_small.gif|200px|right]] | |||
Check<jmol> | |||
<jmolCheckbox> | |||
<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/jd/1jd9_consurf.spt"</scriptWhenChecked> | |||
<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked> | |||
<text>to colour the structure by Evolutionary Conservation</text> | |||
</jmolCheckbox> | |||
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1jd9 ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
To further investigate the mechanism and function of allosteric activation by chloride in some alpha-amylases, the structure of the bacterial alpha-amylase from the psychrophilic micro-organism Pseudoalteromonas haloplanktis in complex with nitrate has been solved at 2.1 A degrees, as well as the structure of the mutants Lys300Gln (2.5 A degrees ) and Lys300Arg (2.25 A degrees ). Nitrate binds strongly to alpha-amylase but is a weak activator. Mutation of the critical chloride ligand Lys300 into Gln results in a chloride-independent enzyme, whereas the mutation into Arg mimics the binding site as is found in animal alpha-amylases with, however, a lower affinity for chloride. These structures reveal that the triangular conformation of the chloride ligands and the nearly equatorial coordination allow the perfect accommodation of planar trigonal monovalent anions such as NO3-, explaining their unusual strong binding. It is also shown that a localized negative charge such as that of Cl-, rather than a delocalized charge as in the case of nitrate, is essential for maximal activation. The chloride-free mutant Lys300Gln indicates that chloride is not mandatory for the catalytic mechanism but strongly increases the reactivity at the active site. Disappearance of the putative catalytic water molecule in this weakly active mutant supports the view that chloride helps to polarize the hydrolytic water molecule and enhances the rate of the second step in the catalytic reaction. | |||
Structural basis of alpha-amylase activation by chloride.,Aghajari N, Feller G, Gerday C, Haser R Protein Sci. 2002 Jun;11(6):1435-41. PMID:12021442<ref>PMID:12021442</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 1jd9" style="background-color:#fffaf0;"></div> | |||
== | ==See Also== | ||
*[[Amylase 3D structures|Amylase 3D structures]] | |||
[[Category: | == References == | ||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Large Structures]] | |||
[[Category: Pseudoalteromonas haloplanktis]] | [[Category: Pseudoalteromonas haloplanktis]] | ||
[[Category: Aghajari N]] | |||
[[Category: Aghajari | [[Category: Haser R]] | ||
[[Category: Haser | |||
Latest revision as of 11:32, 6 November 2024
CRYSTAL STRUCTURE ANALYSIS OF THE MUTANT K300Q OF PSEUDOALTEROMONAS HALOPLANCTIS ALPHA-AMYLASECRYSTAL STRUCTURE ANALYSIS OF THE MUTANT K300Q OF PSEUDOALTEROMONAS HALOPLANCTIS ALPHA-AMYLASE
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTo further investigate the mechanism and function of allosteric activation by chloride in some alpha-amylases, the structure of the bacterial alpha-amylase from the psychrophilic micro-organism Pseudoalteromonas haloplanktis in complex with nitrate has been solved at 2.1 A degrees, as well as the structure of the mutants Lys300Gln (2.5 A degrees ) and Lys300Arg (2.25 A degrees ). Nitrate binds strongly to alpha-amylase but is a weak activator. Mutation of the critical chloride ligand Lys300 into Gln results in a chloride-independent enzyme, whereas the mutation into Arg mimics the binding site as is found in animal alpha-amylases with, however, a lower affinity for chloride. These structures reveal that the triangular conformation of the chloride ligands and the nearly equatorial coordination allow the perfect accommodation of planar trigonal monovalent anions such as NO3-, explaining their unusual strong binding. It is also shown that a localized negative charge such as that of Cl-, rather than a delocalized charge as in the case of nitrate, is essential for maximal activation. The chloride-free mutant Lys300Gln indicates that chloride is not mandatory for the catalytic mechanism but strongly increases the reactivity at the active site. Disappearance of the putative catalytic water molecule in this weakly active mutant supports the view that chloride helps to polarize the hydrolytic water molecule and enhances the rate of the second step in the catalytic reaction. Structural basis of alpha-amylase activation by chloride.,Aghajari N, Feller G, Gerday C, Haser R Protein Sci. 2002 Jun;11(6):1435-41. PMID:12021442[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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