View source for 7bj3


==ScpA from Streptococcus pyogenes, S512A active site mutant==
<StructureSection load='7bj3' size='340' side='right'caption='[[7bj3]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7bj3]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptococcus_pyogenes Streptococcus pyogenes]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7BJ3 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7BJ3 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]] 2.6&#8491;</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>, <scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene>, <scene name='pdbligand=MLA:MALONIC+ACID'>MLA</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=7bj3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7bj3 OCA], [https://pdbe.org/7bj3 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7bj3 RCSB], [https://www.ebi.ac.uk/pdbsum/7bj3 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7bj3 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/C5AP_STRP1 C5AP_STRP1] This virulence factor of S.pyogenes specifically cleaves the human serum chemotaxin C5a at '68-Lys-|-Asp-69' bond near its C-terminus, destroying its ability to serve as a chemoattractant.[UniProtKB:P15926]
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The Streptococcal C5a peptidase (ScpA) specifically inactivates the human complement factor hC5a, a potent anaphylatoxin recently identified as a therapeutic target for treatment of COVID-19 infections. Biologics used to modulate hC5a are predominantly monoclonal antibodies. Here we present data to support an alternative therapeutic approach based on the specific inactivation of hC5a by ScpA in studies using recombinant hC5a (rhC5a). Initial characterization of ScpA confirmed activity in human serum and against rhC5a desArg (rhC5adR), the predominant hC5a form in blood. A new FRET based enzyme assay showed that ScpA cleaved rhC5a at near physiological concentrations (K m 185 nM). Surface Plasmon Resonance (SPR) and Isothermal Titration Calorimetry (ITC) studies established a high affinity ScpA-rhC5a interaction (K D 34 nM, K D ITC 30.8 nM). SPR analyses also showed that substrate binding is dominated (88% of DeltaG degrees bind) by interactions with the bulky N-ter cleavage product (PN, 'core' residues 1-67) with interactions involving the C-ter R74 contributing most of the remaining DeltaG degrees bind. Furthermore, reduced binding affinity following mutation of a subset of positively charged Arginine residues of PN and in the presence of higher salt concentrations, highlighted the importance of electrostatic interactions. These data provide the first in-depth study of the ScpA-C5a interaction and indicate that ScpA's ability to efficiently cleave physiological concentrations of C5a is driven by electrostatic interactions between an exosite on the enzyme and the 'core' of C5a. The results and methods described herein will facilitate engineering of ScpA to enhance its potential as a therapeutic for excessive immune response to infectious disease.

Enzyme kinetic and binding studies identify determinants of specificity for the immunomodulatory enzyme ScpA, a C5a inactivating bacterial protease.,Tecza M, Kagawa TF, Jain M, Cooney JC Comput Struct Biotechnol J. 2021;19:2356-2365. doi: 10.1016/j.csbj.2021.04.024., Epub 2021 Apr 17. PMID:33897974<ref>PMID:33897974</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 7bj3" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Streptococcus pyogenes]]
[[Category: Cooney JC]]
[[Category: Kagawa TF]]
[[Category: O'Connell MR]]