3vs9
From Proteopedia
(Difference between revisions)
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<StructureSection load='3vs9' size='340' side='right' caption='[[3vs9]], [[Resolution|resolution]] 1.99Å' scene=''> | <StructureSection load='3vs9' size='340' side='right' caption='[[3vs9]], [[Resolution|resolution]] 1.99Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
| - | [[3vs9]] is a 8 chain structure with sequence from [http://en.wikipedia.org/wiki/Azovd Azovd]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3VS9 OCA]. <br> | + | <table><tr><td colspan='2'>[[3vs9]] is a 8 chain structure with sequence from [http://en.wikipedia.org/wiki/Azovd Azovd]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3VS9 OCA]. <br> |
| - | <b>[[Ligand|Ligands:]]</b> <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene><br> | + | </td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene><br> |
| - | <b>[[Related_structure|Related:]]</b> [[3vs8|3vs8]]< | + | <tr><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3vs8|3vs8]]</td></tr> |
| - | <b>Activity:</b> <span class='plainlinks'>[http://en.wikipedia.org/wiki/Glucokinase Glucokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.2 2.7.1.2] </span>< | + | <tr><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">arsC, Avin_29530 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=322710 AZOVD])</td></tr> |
| - | <b>Resources:</b> <span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3vs9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3vs9 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3vs9 RCSB], [http://www.ebi.ac.uk/pdbsum/3vs9 PDBsum]</span>< | + | <tr><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Glucokinase Glucokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.2 2.7.1.2] </span></td></tr> |
| + | <tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3vs9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3vs9 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3vs9 RCSB], [http://www.ebi.ac.uk/pdbsum/3vs9 PDBsum]</span></td></tr> | ||
| + | <table> | ||
| + | <div style="background-color:#fffaf0;"> | ||
== Publication Abstract from PubMed == | == Publication Abstract from PubMed == | ||
Type III polyketide synthases (PKSs) show diverse cyclization specificity. We have previously characterized two Azotobacter type III PKSs (ArsB and ArsC) with different cyclization specificity. ArsB and ArsC, which share a high sequence identity (71%), produce alkylresorcinols and alkylpyrones, through aldol condensation and lactonization of the same polyketomethylene intermediate, respectively. Here we identified a key amino acid residue for the cyclization specificity of each enzyme by site-directed mutagenesis. Trp281 of ArsB corresponded to Gly284 of ArsC in the amino acid sequence alignment. The ArsB W281G mutant synthesized alkylpyrone, but not alkylresorcinol. In contrast, the ArsC G284W mutant synthesized alkylresorcinol with a small amount of alkylpyrone. These results indicate that this amino acid residue (Trp281 of ArsB or Gly284 of ArsC) should occupy a critical position for the cyclization specificity of each enzyme. We then determined crystal structures of the wild-type and G284W ArsC proteins at resolutions of 1.76 and 1.99 A, respectively. Comparison of these two ArsC structures indicates that the G284W substitution brings a steric wall to the active site cavity, resulting in a significant reduction of the cavity volume. We postulate that the polyketomethylene intermediate can be folded to a suitable form for aldol condensation only in such a relatively narrow cavity of ArsC G284W (and presumably ArsB). This is the first report on the alteration of cyclization specificity from lactonization to aldol condensation for a type III PKS. The ArsC G284W structure is significant as it is the first reported structure of a microbial resorcinol synthase. | Type III polyketide synthases (PKSs) show diverse cyclization specificity. We have previously characterized two Azotobacter type III PKSs (ArsB and ArsC) with different cyclization specificity. ArsB and ArsC, which share a high sequence identity (71%), produce alkylresorcinols and alkylpyrones, through aldol condensation and lactonization of the same polyketomethylene intermediate, respectively. Here we identified a key amino acid residue for the cyclization specificity of each enzyme by site-directed mutagenesis. Trp281 of ArsB corresponded to Gly284 of ArsC in the amino acid sequence alignment. The ArsB W281G mutant synthesized alkylpyrone, but not alkylresorcinol. In contrast, the ArsC G284W mutant synthesized alkylresorcinol with a small amount of alkylpyrone. These results indicate that this amino acid residue (Trp281 of ArsB or Gly284 of ArsC) should occupy a critical position for the cyclization specificity of each enzyme. We then determined crystal structures of the wild-type and G284W ArsC proteins at resolutions of 1.76 and 1.99 A, respectively. Comparison of these two ArsC structures indicates that the G284W substitution brings a steric wall to the active site cavity, resulting in a significant reduction of the cavity volume. We postulate that the polyketomethylene intermediate can be folded to a suitable form for aldol condensation only in such a relatively narrow cavity of ArsC G284W (and presumably ArsB). This is the first report on the alteration of cyclization specificity from lactonization to aldol condensation for a type III PKS. The ArsC G284W structure is significant as it is the first reported structure of a microbial resorcinol synthase. | ||
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | ||
| + | </div> | ||
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 09:34, 1 May 2014
Crystal structure of type III PKS ArsC mutant
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