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- PDB-8pw3: Mycobacterium smegmatis inosine monophosphate dehydrogenase (IMPD... -
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Open data
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Basic information
Entry | Database: PDB / ID: 8pw3 | ||||||
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Title | Mycobacterium smegmatis inosine monophosphate dehydrogenase (IMPDH) apo form | ||||||
![]() | Inosine-5'-monophosphate dehydrogenase | ||||||
![]() | OXIDOREDUCTASE / Octamer / Apo enzyme / Purine metabolism / IMPDH | ||||||
Function / homology | ![]() IMP dehydrogenase activity / IMP dehydrogenase / GMP biosynthetic process / GTP biosynthetic process / nucleotide binding / metal ion binding Similarity search - Function | ||||||
Biological species | ![]() | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 2.507 Å | ||||||
![]() | Bulvas, O. / Kouba, T. / Pichova, I. | ||||||
Funding support | European Union, 1items
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![]() | ![]() Title: Deciphering the allosteric regulation of mycobacterial inosine-5'-monophosphate dehydrogenase. Authors: Ondřej Bulvas / Zdeněk Knejzlík / Jakub Sýs / Anatolij Filimoněnko / Monika Čížková / Kamila Clarová / Dominik Rejman / Tomáš Kouba / Iva Pichová / ![]() Abstract: Allosteric regulation of inosine 5'-monophosphate dehydrogenase (IMPDH), an essential enzyme of purine metabolism, contributes to the homeostasis of adenine and guanine nucleotides. However, the ...Allosteric regulation of inosine 5'-monophosphate dehydrogenase (IMPDH), an essential enzyme of purine metabolism, contributes to the homeostasis of adenine and guanine nucleotides. However, the precise molecular mechanism of IMPDH regulation in bacteria remains unclear. Using biochemical and cryo-EM approaches, we reveal the intricate molecular mechanism of the IMPDH allosteric regulation in mycobacteria. The enzyme is inhibited by both GTP and (p)ppGpp, which bind to the regulatory CBS domains and, via interactions with basic residues in hinge regions, lock the catalytic core domains in a compressed conformation. This results in occlusion of inosine monophosphate (IMP) substrate binding to the active site and, ultimately, inhibition of the enzyme. The GTP and (p)ppGpp allosteric effectors bind to their dedicated sites but stabilize the compressed octamer by a common mechanism. Inhibition is relieved by the competitive displacement of GTP or (p)ppGpp by ATP allowing IMP-induced enzyme expansion. The structural knowledge and mechanistic understanding presented here open up new possibilities for the development of allosteric inhibitors with antibacterial potential. | ||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 607.7 KB | Display | ![]() |
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PDB format | ![]() | 400.3 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 17988MC ![]() 8q65C ![]() 8qqpC ![]() 8qqqC ![]() 8qqrC ![]() 8qqtC ![]() 8qqvC ![]() 8qqwC ![]() 8qqxC M: map data used to model this data C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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Components
#1: Protein | Mass: 53388.988 Da / Num. of mol.: 8 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() Strain: MC2 155 / Gene: guaB, MSMEG_1602 / Plasmid: pRSFDuet-1 / Production host: ![]() ![]() |
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-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
Component | Name: Octameric assembly of inosine monophosphate dehydrogenase Type: COMPLEX / Entity ID: all / Source: RECOMBINANT | |||||||||||||||||||||||||
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Molecular weight | Value: 0.426658 MDa / Experimental value: NO | |||||||||||||||||||||||||
Source (natural) | Organism: ![]() | |||||||||||||||||||||||||
Source (recombinant) | Organism: ![]() ![]() | |||||||||||||||||||||||||
Buffer solution | pH: 7.5 Details: 50 mM HEPES (pH 7.5), 200 mM KCl, 5 mM DTT,2 mM MgCl2 | |||||||||||||||||||||||||
Buffer component |
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Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES | |||||||||||||||||||||||||
Specimen support | Grid material: GOLD / Grid mesh size: 300 divisions/in. | |||||||||||||||||||||||||
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: TFS KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 165000 X / Nominal defocus max: 3200 nm / Nominal defocus min: 600 nm / Cs: 2.7 mm / Alignment procedure: ZEMLIN TABLEAU |
Specimen holder | Cryogen: NITROGEN |
Image recording | Electron dose: 55 e/Å2 / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
Image scans | Movie frames/image: 40 |
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Processing
EM software |
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CTF correction | Type: PHASE FLIPPING ONLY | ||||||||||||||||||||||||
Particle selection | Num. of particles selected: 5882510 | ||||||||||||||||||||||||
3D reconstruction | Resolution: 2.507 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 550995 / Num. of class averages: 1 / Symmetry type: POINT | ||||||||||||||||||||||||
Atomic model building | B value: 36.96 / Protocol: RIGID BODY FIT / Space: REAL / Target criteria: CC coefficient Details: Initial fitting was done in UCSF ChimeraX. Model refinement was done by iterative cycles of manual fitting with Coot and ISOLDE and automated fitting with phenix.real_space_refine. | ||||||||||||||||||||||||
Atomic model building | Accession code: A0QSU3 / Source name: AlphaFold / Type: in silico model | ||||||||||||||||||||||||
Refinement | Cross valid method: NONE Stereochemistry target values: GeoStd + Monomer Library + CDL v1.2 | ||||||||||||||||||||||||
Displacement parameters | Biso mean: 36.96 Å2 | ||||||||||||||||||||||||
Refine LS restraints |
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