1qa3

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(New page: 200px<br /><applet load="1qa3" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qa3, resolution 2.0&Aring;" /> '''TAILSPIKE PROTEIN, MU...)
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[[Image:1qa3.gif|left|200px]]<br /><applet load="1qa3" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1qa3, resolution 2.0&Aring;" />
 
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'''TAILSPIKE PROTEIN, MUTANT A334I'''<br />
 
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==Overview==
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==TAILSPIKE PROTEIN, MUTANT A334I==
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Four previously isolated mutations in Salmonella phage P22 tailspike, protein were used to study the relationship between protein stability, folding, and function. Tailspike protein binds and hydrolyzes the, repetitive O-antigen structure in Salmonella lipopolysaccharide. Four, mutations (V331G, V331A, A334V, A334I) are known to increase the folding, efficiency, and two of them (at position 331) also increase the thermal, stability of the protein. Octasaccharides comprising two repeating units, of the O-antigens from two different Salmonella strains were employed to, analyze the receptor binding function of the mutant proteins. Their, endorhamnosidase enzymatic activity was assayed with the aid of a, fluorescence-labeled dodecasaccharide. Both V331A and V331G were found to, strongly affect O-antigen binding. Octasaccharide binding affinities of, the mutant proteins are reduced tenfold and 200-fold, corresponding to a, loss of 17% and 36% of the standard free energy of binding, respectively., Both mutations at position 334 affected O-antigen binding only slightly, (DeltaDeltaG(0)B approximately 1 kJ/mol), but these mutations reduce the, thermal stability of the protein. The observed effects on the, endoglycosidase activity are fully explained by the changes in substrate, binding, suggesting that neither of the mutations affect the catalytic, rate. Crystal structures of all four mutants were determined to a, resolution of 2.0 A. Except for the partly or completely missing, side-chain, no significant changes compared to the wild-type protein, structure were found for the mutants at position 331, whereas a small but, significant backbone displacement around the mutation site in A334V and, A334I may explain the observed thermal destabilization.
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<StructureSection load='1qa3' size='340' side='right'caption='[[1qa3]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1qa3]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Salmonella_virus_P22 Salmonella virus P22]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QA3 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QA3 FirstGlance]. <br>
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</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&#8491;</td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1qa3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qa3 OCA], [https://pdbe.org/1qa3 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qa3 RCSB], [https://www.ebi.ac.uk/pdbsum/1qa3 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qa3 ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/FIBER_BPP22 FIBER_BPP22] Structural component of the short non-contractile tail. The tail comprises six fibers that mediate primary attachment to the host cell lipopolysaccharides (LPS) and display endorhamnosidase enzymatic activity, hydrolyzing the alpha-1,3-O-glycosidic linkage between rhamnose and galactose of the O-antigen polysaccharide. Digestion of the LPS brings the capsid near the cell outer membrane.<ref>PMID:12837775</ref> <ref>PMID:20817910</ref>
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==About this Structure==
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==See Also==
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1QA3 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Yersinia_phage_py54 Yersinia phage py54]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QA3 OCA].
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*[[Tailspike protein 3D structures|Tailspike protein 3D structures]]
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== References ==
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==Reference==
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<references/>
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Mutations improving the folding of phage P22 tailspike protein affect its receptor binding activity., Baxa U, Steinbacher S, Weintraub A, Huber R, Seckler R, J Mol Biol. 1999 Oct 29;293(3):693-701. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10543960 10543960]
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__TOC__
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[[Category: Single protein]]
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</StructureSection>
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[[Category: Yersinia phage py54]]
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[[Category: Large Structures]]
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[[Category: Baxa, U.]]
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[[Category: Salmonella virus P22]]
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[[Category: Huber, R.]]
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[[Category: Baxa U]]
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[[Category: Seckler, R.]]
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[[Category: Huber R]]
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[[Category: Steinbacher, S.]]
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[[Category: Seckler R]]
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[[Category: Weintraub, A.]]
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[[Category: Steinbacher S]]
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[[Category: virus/viral protein]]
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[[Category: Weintraub A]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 00:31:05 2007''
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TAILSPIKE PROTEIN, MUTANT A334I

PDB ID 1qa3

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