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==THE INTRODUCTION OF STRAIN AND ITS EFFECTS ON THE STRUCTURE AND STABILITY OF T4 LYSOZYME==
==THE INTRODUCTION OF STRAIN AND ITS EFFECTS ON THE STRUCTURE AND STABILITY OF T4 LYSOZYME==
<StructureSection load='1qtb' size='340' side='right' caption='[[1qtb]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
<StructureSection load='1qtb' size='340' side='right'caption='[[1qtb]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[1qtb]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Bpt4 Bpt4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QTB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1QTB FirstGlance]. <br>
<table><tr><td colspan='2'>[[1qtb]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_virus_T4 Escherichia virus T4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QTB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QTB FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HED:2-HYDROXYETHYL+DISULFIDE'>HED</scene></td></tr>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.9&#8491;</td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1qsb|1qsb]], [[1qs5|1qs5]], [[1qs9|1qs9]], [[1qtc|1qtc]], [[1qtd|1qtd]], [[1qth|1qth]]</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HED:2-HYDROXYETHYL+DISULFIDE'>HED</scene></td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Lysozyme Lysozyme], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.17 3.2.1.17] </span></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=1qtb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qtb OCA], [https://pdbe.org/1qtb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qtb RCSB], [https://www.ebi.ac.uk/pdbsum/1qtb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qtb ProSAT]</span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1qtb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qtb OCA], [http://pdbe.org/1qtb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1qtb RCSB], [http://www.ebi.ac.uk/pdbsum/1qtb PDBsum]</span></td></tr>
</table>
</table>
== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/LYS_BPT4 LYS_BPT4]] Helps to release the mature phage particles from the cell wall by breaking down the peptidoglycan.  
[https://www.uniprot.org/uniprot/ENLYS_BPT4 ENLYS_BPT4] Endolysin with lysozyme activity that degrades host peptidoglycans and participates with the holin and spanin proteins in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the peptidoglycan layer.<ref>PMID:22389108</ref>
== Evolutionary Conservation ==
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
Check<jmol>
   <jmolCheckbox>
   <jmolCheckbox>
     <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qt/1qtb_consurf.spt"</scriptWhenChecked>
     <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qt/1qtb_consurf.spt"</scriptWhenChecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <text>to colour the structure by Evolutionary Conservation</text>
     <text>to colour the structure by Evolutionary Conservation</text>
   </jmolCheckbox>
   </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/chain_selection.php?pdb_ID=2ata ConSurf].
</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=1qtb ConSurf].
<div style="clear:both"></div>
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In order to try to better understand the role played by strain in the structure and stability of a protein a series of "small-to-large" mutations was made within the core of T4 lysozyme. Three different alanine residues, one involved in backbone contacts, one in side-chain contacts, and the third adjacent to a small cavity, were each replaced with subsets of the larger residues, Val, Leu, Ile, Met, Phe and Trp. As expected, the protein is progressively destabilized as the size of the introduced side-chain becomes larger. There does, however, seem to be a limit to the destabilization, suggesting that a protein of a given size may be capable of maintaining only a certain amount of strain. The changes in stability vary greatly from site to site. Substitution of larger residues for both Ala42 and Ala98 substantially destabilize the protein, even though the primary contacts in one case are predominantly with side-chain atoms and in the other with backbone. The results suggest that it is neither practical nor meaningful to try to separate the effects of introduced strain on side-chains from the effects on the backbone. Substitutions at Ala129 are much less destabilizing than at sites 42 or 98. This is most easily understood in terms of the pre-existing cavity, which provides partial space to accommodate the introduced side-chains. Crystal structures were obtained for a number of the mutants. These show that the changes in structure to accommodate the introduced side-chains usually consist of essentially rigid-body displacements of groups of linked atoms, achieved through relatively small changes in torsion angles. On rare occasions, a side-chain close to the site of substitution may change to a different rotamer. When such rotomer changes occur, they permit the structure to dissipate strain by a response that is plastic rather than elastic. In one case, a surface loop moves 1.2 A, not in direct response to a mutation, but in an interaction mediated via an intermolecular contact. It illustrates how the structure of a protein can be modified by crystal contacts.
The introduction of strain and its effects on the structure and stability of T4 lysozyme.,Liu R, Baase WA, Matthews BW J Mol Biol. 2000 Jan 7;295(1):127-45. PMID:10623513<ref>PMID:10623513</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 1qtb" style="background-color:#fffaf0;"></div>


==See Also==
==See Also==
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__TOC__
__TOC__
</StructureSection>
</StructureSection>
[[Category: Bpt4]]
[[Category: Escherichia virus T4]]
[[Category: Lysozyme]]
[[Category: Large Structures]]
[[Category: Baase, W A]]
[[Category: Baase WA]]
[[Category: Liu, R]]
[[Category: Liu R]]
[[Category: Matthews, B W]]
[[Category: Matthews BW]]
[[Category: Hydrolase]]
[[Category: Mutant]]
[[Category: Stability]]
[[Category: Strain]]
[[Category: T4 lysozyme]]

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