View source for 4mi4


==Crystal structure of spermidine N-acetyltransferase from Vibrio cholerae in complex with spermine==
<StructureSection load='4mi4' size='340' side='right'caption='[[4mi4]], [[Resolution|resolution]] 1.85&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4mi4]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Vibrio_cholerae_O1_biovar_El_Tor_str._N16961 Vibrio cholerae O1 biovar El Tor str. N16961]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4MI4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4MI4 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]] 1.848&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SPM:SPERMINE'>SPM</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=4mi4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4mi4 OCA], [https://pdbe.org/4mi4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4mi4 RCSB], [https://www.ebi.ac.uk/pdbsum/4mi4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4mi4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ATDA_VIBCH ATDA_VIBCH] Involved in the protection against polyamine toxicity by regulating their concentration. Catalyzes the transfer of an acetyl group from acetyl coenzyme A (AcCoA) to the primary amino groups of spermidine to yield N(1)- and N(8)-acetylspermidine. It can use polyamines such as spermine and N(1)-acetylspermine, but not putrescine or cadaverine.<ref>PMID:23184347</ref> <ref>PMID:25623305</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Spermidine N-acetyltransferase, encoded by the gene speG, catalyzes the initial step in the degradation of polyamines and is a critical enzyme for determining the polyamine concentrations in bacteria. In Escherichia coli, studies have shown that SpeG is the enzyme responsible for acetylating spermidine under stress conditions and for preventing spermidine toxicity. Not all bacteria contain speG, and many bacterial pathogens have developed strategies to either acquire or silence it for pathogenesis. Here, we present thorough kinetic analyses combined with structural characterization of the VCA0947 SpeG enzyme from the important human pathogen Vibrio cholerae. Our studies revealed the unexpected presence of a previously unknown allosteric site and an unusual dodecameric structure for a member of the Gcn5-related N-acetyltransferase superfamily. We show that SpeG forms dodecamers in solution and in crystals and describe its three-dimensional structure in several ligand-free and liganded structures. Importantly, these structural data define the first view of a polyamine bound in an allosteric site of an N-acetyltransferase. Kinetic characterization of SpeG from V. cholerae showed that it acetylates spermidine and spermine. The behavior of this enzyme is complex and exhibits sigmoidal curves and substrate inhibition. We performed a detailed non-linear regression kinetic analysis to simultaneously fit families of substrate saturation curves to uncover a simple kinetic mechanism that explains the apparent complexity of this enzyme. Our results provide a fundamental understanding of the bacterial SpeG enzyme, which will be key toward understanding the regulation of polyamine levels in bacteria during pathogenesis.

A Novel Polyamine Allosteric Site of SpeG from Vibrio cholerae Is Revealed by Its Dodecameric Structure.,Filippova EV, Kuhn ML, Osipiuk J, Kiryukhina O, Joachimiak A, Ballicora MA, Anderson WF J Mol Biol. 2015 Mar 27;427(6 Pt B):1316-34. doi: 10.1016/j.jmb.2015.01.009. Epub, 2015 Jan 23. PMID:25623305<ref>PMID:25623305</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4mi4" style="background-color:#fffaf0;"></div>

==See Also==
*[[Spermidine/spermine N-acetyltransferase|Spermidine/spermine N-acetyltransferase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Vibrio cholerae O1 biovar El Tor str. N16961]]
[[Category: Anderson WF]]
[[Category: Filippova EV]]
[[Category: Kiryukhina O]]
[[Category: Kuhn ML]]
[[Category: Minasov G]]
[[Category: Shuvalova L]]