6qns: Difference between revisions

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 <StructureSection load='6qns' size='340' side='right'caption='[[6qns]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
 == Structural highlights ==
-<table><tr><td colspan='2'>[[6qns]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6QNS OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6QNS FirstGlance]. <br>
+<table><tr><td colspan='2'>[[6qns]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"bacillus_botulinus"_van_ermengem_1896 "bacillus botulinus" van ermengem 1896]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6QNS OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6QNS FirstGlance]. <br>
 </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BGC:BETA-D-GLUCOSE'>BGC</scene>, <scene name='pdbligand=GAL:BETA-D-GALACTOSE'>GAL</scene>, <scene name='pdbligand=NGA:N-ACETYL-D-GALACTOSAMINE'>NGA</scene>, <scene name='pdbligand=SIA:O-SIALIC+ACID'>SIA</scene></td></tr>
+<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">botB ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1491 "Bacillus botulinus" van Ermengem 1896])</td></tr>
 <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Bontoxilysin Bontoxilysin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.24.69 3.4.24.69] </span></td></tr>
 <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6qns FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6qns OCA], [http://pdbe.org/6qns PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6qns RCSB], [http://www.ebi.ac.uk/pdbsum/6qns PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6qns ProSAT]</span></td></tr>
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 == Function ==
 [[http://www.uniprot.org/uniprot/BXB_CLOBO BXB_CLOBO]] Botulinum toxin acts by inhibiting neurotransmitter release. It binds to peripheral neuronal synapses, is internalized and moves by retrograde transport up the axon into the spinal cord where it can move between postsynaptic and presynaptic neurons. It inhibits neurotransmitter release by acting as a zinc endopeptidase that cleaves the '76-Gln-|-Phe-77' bond of synaptobrevin-2. [[http://www.uniprot.org/uniprot/SYT1_HUMAN SYT1_HUMAN]] May have a regulatory role in the membrane interactions during trafficking of synaptic vesicles at the active zone of the synapse. It binds acidic phospholipids with a specificity that requires the presence of both an acidic head group and a diacyl backbone. A Ca(2+)-dependent interaction between synaptotagmin and putative receptors for activated protein kinase C has also been reported. It can bind to at least three additional proteins in a Ca(2+)-independent manner; these are neurexins, syntaxin and AP2.
+<div style="background-color:#fffaf0;">
+== Publication Abstract from PubMed ==
+Botulinum neurotoxins (BoNTs) are a family of bacterial toxins with seven major serotypes (BoNT/A-G). The ability of these toxins to target and bind to motor nerve terminals is a key factor determining their potency and efficacy. Among these toxins, BoNT/B is one of the two types approved for medical and cosmetic uses. Besides binding to well-established receptors, an extended loop in the C-terminal receptor-binding domain (HC) of BoNT/B (HC/B) has been proposed to also contribute to toxin binding to neurons by interacting with lipid membranes (termed lipid-binding loop [LBL]). Analogous loops exist in the HCs of BoNT/C, D, G, and a chimeric toxin DC. However, it has been challenging to detect and characterize binding of LBLs to lipid membranes. Here, using the nanodisc system and biolayer interferometry assays, we find that HC/DC, C, and G, but not HC/B and HC/D, are capable of binding to receptor-free lipids directly, with HC/DC having the highest level of binding. Mutagenesis studies demonstrate the critical role of consecutive aromatic residues at the tip of the LBL for binding of HC/DC to lipid membranes. Taking advantage of this insight, we then create a "gain-of-function" mutant HC/B by replacing two nonaromatic residues at the tip of its LBL with tryptophan. Cocrystallization studies confirm that these two tryptophan residues do not alter the structure of HC/B or the interactions with its receptors. Such a mutated HC/B gains the ability to bind receptor-free lipid membranes and shows enhanced binding to cultured neurons. Finally, full-length BoNT/B containing two tryptophan mutations in its LBL, together with two additional mutations (E1191M/S1199Y) that increase binding to human receptors, is produced and evaluated in mice in vivo using Digit Abduction Score assays. This mutant toxin shows enhanced efficacy in paralyzing local muscles at the injection site and lower systemic diffusion, thus extending both safety range and duration of paralysis compared with the control BoNT/B. These findings establish a mechanistic understanding of LBL-lipid interactions and create a modified BoNT/B with improved therapeutic efficacy.
+Characterization of a membrane binding loop leads to engineering botulinum neurotoxin B with improved therapeutic efficacy.,Yin L, Masuyer G, Zhang S, Zhang J, Miyashita SI, Burgin D, Lovelock L, Coker SF, Fu TM, Stenmark P, Dong M PLoS Biol. 2020 Mar 17;18(3):e3000618. doi: 10.1371/journal.pbio.3000618., eCollection 2020 Mar. PMID:32182233<ref>PMID:32182233</ref>
+From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
+</div>
+<div class="pdbe-citations 6qns" style="background-color:#fffaf0;"></div>
+== References ==
+<references/>
 __TOC__
 </StructureSection>
+[[Category: Bacillus botulinus van ermengem 1896]]
 [[Category: Bontoxilysin]]
 [[Category: Large Structures]]