6ok1: Difference between revisions
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<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=6ok1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ok1 OCA], [http://pdbe.org/6ok1 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6ok1 RCSB], [http://www.ebi.ac.uk/pdbsum/6ok1 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6ok1 ProSAT]</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=6ok1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ok1 OCA], [http://pdbe.org/6ok1 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6ok1 RCSB], [http://www.ebi.ac.uk/pdbsum/6ok1 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6ok1 ProSAT]</span></td></tr> | ||
</table> | </table> | ||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
An aldolase from the bile acid-degrading actinobacterium Thermomonospora curvata catalyzes the C-C bond cleavage of an isopropyl-CoA side chain from the D-ring of the steroid metabolite 17-hydroxy-3-oxo-4-pregnene-20-carboxyl-CoA (17-HOPC-CoA). Like its homolog from Mycobacterium tuberculosis, the T. curvata aldolase is a protein complex of Ltp2 with a DUF35 domain derived from the C-terminal domain of a hydratase (ChsH2DUF35) that catalyzes the preceding step in the pathway. We determined the structure of the Ltp2-ChsH2DUF35 complex at 1.7 A resolution using zinc-single anomalous diffraction (zinc-SAD). The enzyme adopts an alphabetabetaalpha organization, with the two Ltp2 protomers forming a central dimer, and the two ChsH2DUF35 protomers being at the periphery. Docking experiments suggested that Ltp2 forms a tight complex with the hydratase, but that each enzyme retains an independent CoA-binding site. Ltp2 adopted a fold similar to those in thiolases; however, instead of forming a deep tunnel, the Ltp2 active site formed an elongated cleft large enough to accommodate 17-HOPC-CoA. The active site lacked the two cysteines that served as the nucleophile and general base in thiolases and replaced a pair of oxyanion-hole histidine residues with Tyr-246 and Tyr-344. Phenylalanine replacement of either of these residues decreased aldolase catalytic activity at least 400-fold. On the basis of a 17-HOPC-CoA-docked model, we propose a catalytic mechanism where Tyr-294 acts as the general base abstracting a proton from the D-ring hydroxyl of 17-HOPC-CoA and Tyr-344 as the general acid that protonates the propionyl-CoA anion following C-C bond cleavage. | |||
The steroid side chain-cleaving aldolase Ltp2-ChsH2DUF35 is a thiolase superfamily member with a radically repurposed active site.,Aggett R, Mallette E, Gilbert SE, Vachon MA, Schroeter KL, Kimber MS, Seah SYK J Biol Chem. 2019 Jun 16. pii: RA119.008889. doi: 10.1074/jbc.RA119.008889. PMID:31209106<ref>PMID:31209106</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 6ok1" style="background-color:#fffaf0;"></div> | |||
== References == | |||
<references/> | |||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
Revision as of 09:56, 3 July 2019
Ltp2-ChsH2(DUF35) aldolaseLtp2-ChsH2(DUF35) aldolase
Structural highlights
Publication Abstract from PubMedAn aldolase from the bile acid-degrading actinobacterium Thermomonospora curvata catalyzes the C-C bond cleavage of an isopropyl-CoA side chain from the D-ring of the steroid metabolite 17-hydroxy-3-oxo-4-pregnene-20-carboxyl-CoA (17-HOPC-CoA). Like its homolog from Mycobacterium tuberculosis, the T. curvata aldolase is a protein complex of Ltp2 with a DUF35 domain derived from the C-terminal domain of a hydratase (ChsH2DUF35) that catalyzes the preceding step in the pathway. We determined the structure of the Ltp2-ChsH2DUF35 complex at 1.7 A resolution using zinc-single anomalous diffraction (zinc-SAD). The enzyme adopts an alphabetabetaalpha organization, with the two Ltp2 protomers forming a central dimer, and the two ChsH2DUF35 protomers being at the periphery. Docking experiments suggested that Ltp2 forms a tight complex with the hydratase, but that each enzyme retains an independent CoA-binding site. Ltp2 adopted a fold similar to those in thiolases; however, instead of forming a deep tunnel, the Ltp2 active site formed an elongated cleft large enough to accommodate 17-HOPC-CoA. The active site lacked the two cysteines that served as the nucleophile and general base in thiolases and replaced a pair of oxyanion-hole histidine residues with Tyr-246 and Tyr-344. Phenylalanine replacement of either of these residues decreased aldolase catalytic activity at least 400-fold. On the basis of a 17-HOPC-CoA-docked model, we propose a catalytic mechanism where Tyr-294 acts as the general base abstracting a proton from the D-ring hydroxyl of 17-HOPC-CoA and Tyr-344 as the general acid that protonates the propionyl-CoA anion following C-C bond cleavage. The steroid side chain-cleaving aldolase Ltp2-ChsH2DUF35 is a thiolase superfamily member with a radically repurposed active site.,Aggett R, Mallette E, Gilbert SE, Vachon MA, Schroeter KL, Kimber MS, Seah SYK J Biol Chem. 2019 Jun 16. pii: RA119.008889. doi: 10.1074/jbc.RA119.008889. PMID:31209106[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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