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| - | [[Image:2fhn.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_2fhn| PDB=2fhn | SCENE= }} | | {{STRUCTURE_2fhn| PDB=2fhn | SCENE= }} |
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| - | '''Avidin related protein AVR4 (C122S, K109I mutant) in complex with BNA'''
| + | ===Avidin related protein AVR4 (C122S, K109I mutant) in complex with BNA=== |
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| - | ==Overview==
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| - | The hydrolysis of biotinyl p-nitrophenyl ester (BNP) by a series of avidin derivatives was examined. Surprisingly, a hyperthermostable avidin-related protein (AVR4) was shown to display extraordinary yet puzzling hydrolytic activity. In order to evaluate the molecular determinants that contribute to the reaction, the crystal structure of AVR4 was compared with those of avidin, streptavidin and key mutants of the two proteins in complex with biotinyl p-nitroanilide (BNA), the inert amide analogue of BNP. The structures revealed that a critical lysine residue contributes to the hydrolysis of BNP by avidin but has only a minor contribution to the AVR4-mediated reaction. Indeed, the respective rates of hydrolysis among the different avidins reflect several molecular parameters, including binding-site architecture, the availability of the ligand to solvent and the conformation of the ligand and consequent susceptibility to efficient nucleophilic attack. In avidin, the interaction of BNP with Lys111 and disorder of the L3,4 loop (and consequent solvent availability) together comprise the major driving force behind the hydrolysis, whereas in AVR4 the status of the ligand (the pseudo-substrate) is a major distinguishing feature. In the latter protein, a unique conformation of the L3,4 loop restrains the pseudo-substrate, thereby exposing the carbonyl carbon atom to nucleophilic attack. In addition, due to its conformation, the pseudo-substrate in the AVR4 complex cannot interact with the conserved lysine analogue (Lys109); instead, this function is superseded by polar interactions with Arg112. The results demonstrate that, in highly similar proteins, different residues can perform the same function and that subtle differences in the active-site architecture of such proteins can result in alternative modes of reaction.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_16546211}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 16546211 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_16546211}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Hydrolytic activity]] | | [[Category: Hydrolytic activity]] |
| | [[Category: Streptavidin]] | | [[Category: Streptavidin]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 03:54:37 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 10:33:27 2008'' |
Revision as of 07:33, 28 July 2008
Template:STRUCTURE 2fhn
Avidin related protein AVR4 (C122S, K109I mutant) in complex with BNA
Template:ABSTRACT PUBMED 16546211
About this Structure
2FHN is a Single protein structure of sequence from Gallus gallus. Full crystallographic information is available from OCA.
Reference
Factors dictating the pseudocatalytic efficiency of avidins., Prizant M, Eisenberg-Domovich Y, Hytonen VP, Kulomaa MS, Wilchek M, Bayer EA, Livnah O, J Mol Biol. 2006 May 5;358(3):754-63. Epub 2006 Mar 3. PMID:16546211
Page seeded by OCA on Mon Jul 28 10:33:27 2008
