Journal:FEBS Open Bio:1
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Biotin-dependent acetyl-CoA carboxylases catalyze the committed step in type II fatty acid biosynthesis, the main route for production of membrane phospholipids in bacteria, and are considered a key target for antibacterial drug discovery. Here we describe the first structure of AccA3, an essential component of the acetyl-CoA carboxylase system in ''Mycobacterium tuberculosis'' (MTb). The structure, sequence comparisons, and modeling of ligand-bound states reveal that the ATP cosubstrate-binding site shows distinct differences compared to other bacterial and eukaryotic biotin carboxylases, including all human homologs. This suggests the possibility to design MTb AccA3 subtype-specific inhibitors. | Biotin-dependent acetyl-CoA carboxylases catalyze the committed step in type II fatty acid biosynthesis, the main route for production of membrane phospholipids in bacteria, and are considered a key target for antibacterial drug discovery. Here we describe the first structure of AccA3, an essential component of the acetyl-CoA carboxylase system in ''Mycobacterium tuberculosis'' (MTb). The structure, sequence comparisons, and modeling of ligand-bound states reveal that the ATP cosubstrate-binding site shows distinct differences compared to other bacterial and eukaryotic biotin carboxylases, including all human homologs. This suggests the possibility to design MTb AccA3 subtype-specific inhibitors. | ||
| - | ''Mycobacterium tuberculosis'' <scene name='76/763765/Cv/2'>AccA3 adopts the ATPgrasp superfamily fold</scene>, and crystallized as a <scene name='76/763765/Cv/3'>dimer in the asymmetric unit</scene>. <scene name='76/763765/Cv/4'>The | + | ''Mycobacterium tuberculosis'' <scene name='76/763765/Cv/2'>AccA3 adopts the ATPgrasp superfamily fold</scene>, and crystallized as a <scene name='76/763765/Cv/3'>dimer in the asymmetric unit</scene>. <scene name='76/763765/Cv/4'>The ordered structure of domain B is missing in chain B</scene>. |
Previous structures have shown defined ‘open’ and ‘closed’ states of the B-domain<ref>pmid 19213731</ref><ref>pmid 7915138</ref>. In addition, the biotin carboxylase domain of pyruvate carboxylase from ''Bacillus thermodenitrificans'' displays what appears to be an intermediate, but defined, conformation <ref>pmid 17642515</ref>. In the current structure, however, while <scene name='76/763765/Cv/6'>protomer A</scene> represents the previously observed ‘closed’ state, <scene name='76/763765/Cv/7'>protomer B</scene> represent a different structural state where no conformation is present in high enough occupancy to be possible to reliably model. MTb AccA3, subunit A (blue) and subunit B (yellow), unbound BDC from Escherichia coli (gray) (PDB [[1bnc]]). Based on the location of the segment of positive difference density relative to protomer B, it is, however, clear that the location of the B-domain in the partially occupied structural state that gives rise to this density is not the same as either the previously described ‘closed’ or ‘open’ states. Rather, the density suggests an even more extended conformation of the B-domain relative to the rest of the protein. Together, the most likely interpretation of the combined structural data of biotin-dependent carboxylases is that the B-domain is dynamic over a continuum of conformations, or several defined conformations. | Previous structures have shown defined ‘open’ and ‘closed’ states of the B-domain<ref>pmid 19213731</ref><ref>pmid 7915138</ref>. In addition, the biotin carboxylase domain of pyruvate carboxylase from ''Bacillus thermodenitrificans'' displays what appears to be an intermediate, but defined, conformation <ref>pmid 17642515</ref>. In the current structure, however, while <scene name='76/763765/Cv/6'>protomer A</scene> represents the previously observed ‘closed’ state, <scene name='76/763765/Cv/7'>protomer B</scene> represent a different structural state where no conformation is present in high enough occupancy to be possible to reliably model. MTb AccA3, subunit A (blue) and subunit B (yellow), unbound BDC from Escherichia coli (gray) (PDB [[1bnc]]). Based on the location of the segment of positive difference density relative to protomer B, it is, however, clear that the location of the B-domain in the partially occupied structural state that gives rise to this density is not the same as either the previously described ‘closed’ or ‘open’ states. Rather, the density suggests an even more extended conformation of the B-domain relative to the rest of the protein. Together, the most likely interpretation of the combined structural data of biotin-dependent carboxylases is that the B-domain is dynamic over a continuum of conformations, or several defined conformations. | ||
Revision as of 11:08, 6 November 2017
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- ↑ Bennett M, Hogbom M. Crystal structure of the essential biotin-dependent carboxylase AccA3 from Mycobacterium tuberculosis. FEBS Open Bio. 2017 Apr 4;7(5):620-626. doi: 10.1002/2211-5463.12212. eCollection, 2017 May. PMID:28469974 doi:http://dx.doi.org/10.1002/2211-5463.12212
- ↑ Chou CY, Yu LP, Tong L. Crystal structure of biotin carboxylase in complex with substrates and implications for its catalytic mechanism. J Biol Chem. 2009 Apr 24;284(17):11690-7. Epub 2009 Feb 12. PMID:19213731 doi:10.1074/jbc.M805783200
- ↑ Waldrop GL, Rayment I, Holden HM. Three-dimensional structure of the biotin carboxylase subunit of acetyl-CoA carboxylase. Biochemistry. 1994 Aug 30;33(34):10249-56. PMID:7915138
- ↑ Kondo S, Nakajima Y, Sugio S, Sueda S, Islam MN, Kondo H. Structure of the biotin carboxylase domain of pyruvate carboxylase from Bacillus thermodenitrificans. Acta Crystallogr D Biol Crystallogr. 2007 Aug;63(Pt 8):885-90. Epub 2007, Jul 17. PMID:17642515 doi:10.1107/S0907444907029423
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