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New page: left|200px<br /><applet load="3b50" size="350" color="white" frame="true" align="right" spinBox="true" caption="3b50, resolution 1.400Å" /> '''Structure of H. inf...
 
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[[Image:3b50.jpg|left|200px]]<br /><applet load="3b50" size="350" color="white" frame="true" align="right" spinBox="true"
caption="3b50, resolution 1.400&Aring;" />
'''Structure of H. influenzae sialic acid binding protein bound to Neu5Ac.'''<br />


==Overview==
==Structure of H. influenzae sialic acid binding protein bound to Neu5Ac.==
Nontypeable Haemophilus influenzae is an opportunistic human pathogen, causing otitis media in children and chronic bronchitis and pneumonia in, patients with chronic obstructive pulmonary disease. The outer membrane of, nontypeable H. influenzae is dominated by lipooligosaccharides (LOS), many, of which incorporate sialic acid as a terminal non-reducing sugar. Sialic, acid has been demonstrated to be an important factor in the survival of, the bacteria within the host environment. H. influenzae is incapable of, synthesizing sialic acid and is dependent on scavenging free sialic acid, from the host environment. To achieve this, H. influenzae utilizes a, tripartite ATP-independent periplasmic transporter. In this paper, we, characterize the binding site of the extracytoplasmic solute receptor, (SiaP) from nontypeable H. influenzae strain 2019. A crystal structure of, Neu5Ac-bound SiaP was determined to 1.4 A resolution. Thermodynamic, characterization of Neu5Ac binding shows this interaction is enthalpically, driven with a substantial unfavorable contribution from entropy. This is, expected because the binding of SiaP to Neu5AC is mediated by numerous, hydrogen bonds and has several buried water molecules. Point mutations, targeting specific amino acids were introduced in the putative binding, site. Complementation with the mutated siaP constructs resulted either in, full, partial, or no complementation, depending on the role of specific, residues. Mass spectrometry analysis of the O-deacylated LOS of the R127K, point mutation confirmed the observation of reduced incorporation of, Neu5Ac into the LOS. The decreased ability of H. influenzae to import, sialic acid had negative effects on resistance to complement-mediated, killing and viability of biofilms in vitro, confirming the importance of, sialic acid transport to the bacterium.
<StructureSection load='3b50' size='340' side='right'caption='[[3b50]], [[Resolution|resolution]] 1.40&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[3b50]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Haemophilus_influenzae Haemophilus influenzae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3B50 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3B50 FirstGlance]. <br>
3B50 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Haemophilus_influenzae Haemophilus influenzae] with <scene name='pdbligand=SLB:'>SLB</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3B50 OCA].  
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.4&#8491;</td></tr>
 
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SLB:5-N-ACETYL-BETA-D-NEURAMINIC+ACID'>SLB</scene></td></tr>
==Reference==
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3b50 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3b50 OCA], [https://pdbe.org/3b50 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3b50 RCSB], [https://www.ebi.ac.uk/pdbsum/3b50 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3b50 ProSAT]</span></td></tr>
Characterization of the N-acetyl-5-neuraminic acid binding site of the extracytoplasmic solute receptor (SiaP) of nontypeable Haemophilus influenzae strain 2019., Johnston JW, Coussens NP, Allen S, Houtman JC, Turner KH, Zaleski A, Ramaswamy S, Gibson BW, Apicella MA, J Biol Chem. 2007 Oct 18;. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17947229 17947229]
</table>
== Function ==
[https://www.uniprot.org/uniprot/SIAP_HAEIN SIAP_HAEIN] Part of the tripartite ATP-independent periplasmic (TRAP) transport system SiaPT involved in the uptake of sialic acid. This protein specifically binds sialic acid with high affinity.
== 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/b5/3b50_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=3b50 ConSurf].
<div style="clear:both"></div>
__TOC__
</StructureSection>
[[Category: Haemophilus influenzae]]
[[Category: Haemophilus influenzae]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Apicella, M.A.]]
[[Category: Apicella MA]]
[[Category: Coussens, N.P.]]
[[Category: Coussens NP]]
[[Category: Johnston, J.W.]]
[[Category: Johnston JW]]
[[Category: Ramaswamy, S.]]
[[Category: Ramaswamy S]]
[[Category: SLB]]
[[Category: periplasmic binding protein]]
[[Category: sugar transport]]
[[Category: transport]]
[[Category: transport protein]]
[[Category: trap]]
 
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Retrieved from "https://proteopedia.org/3b50"