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==Structure of signal peptide peptidase A with C-termini bound in the active sites: insights into specificity, self-processing and regulation==
<StructureSection load='4kwb' size='340' side='right'caption='[[4kwb]], [[Resolution|resolution]] 2.39&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4kwb]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_subtilis_subsp._subtilis_str._168 Bacillus subtilis subsp. subtilis str. 168]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4KWB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4KWB 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]] 2.39&#8491;</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=4kwb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4kwb OCA], [https://pdbe.org/4kwb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4kwb RCSB], [https://www.ebi.ac.uk/pdbsum/4kwb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4kwb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SPPA_BACSU SPPA_BACSU] Digestion of cleaved signal peptides (By similarity). Required for efficient processing of precursors under conditions of hyper-secretion.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Bacterial signal peptide peptidase A (SppA) is a membrane-bound enzyme that utilizes a serine/lysine catalytic dyad mechanism to cleave remnant signal peptides within the cellular membrane. Bacillus subtilis SppA (SppABS) oligomerizes into a homo-octameric dome-shaped complex with eight active sites, located at the interface between each protomer. In this study, we show that SppABS self-processes its own C-termini. We have determined the crystal structure of a proteolytically stable fragment of SppABSK199A that has its C-terminal peptide bound in each of the eight active sites, creating a perfect circle of peptides. Substrate specificity pockets S1, S3, and S2' are identified and accommodate C-terminal residues Tyr331, Met329, and Tyr333, respectively. Tyr331 at the P1 position is conserved among most Bacillus species. The structure reveals that the C-terminus binds within the substrate-binding grooves in an antiparallel beta-sheet fashion. We show, by C-terminal truncations, that the C-terminus is not essential for oligomeric assembly. Kinetic analysis shows that a synthetic peptide corresponding to the C-terminus of SppABS competes with a fluorometric peptide substrate for the SppABS active site. A model is proposed for how the C-termini of SppA may function in the regulation of this membrane-bound self-compartmentalized protease.

Structure of signal peptide peptidase A with C-termini bound in the active sites: insights into specificity, self-processing, and regulation.,Nam SE, Paetzel M Biochemistry. 2013 Dec 10;52(49):8811-22. doi: 10.1021/bi4011489. Epub 2013 Nov, 25. PMID:24228759<ref>PMID:24228759</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4kwb" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Bacillus subtilis subsp. subtilis str. 168]]
[[Category: Large Structures]]
[[Category: Nam SE]]
[[Category: Paetzel M]]