3G22

Crystal structure of the mutant D70N of orotidine 5'-monophosphate decarboxylase from Methanobacterium thermoautotrophicum complexed with uridine 5'-monophosphate

• PDB DOI: https://doi.org/10.2210/pdb3G22/pdb

• Classification: LYASE
• Organism(s): Methanothermobacter thermautotrophicus str. Delta H
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2009-01-30 Released: 2009-06-23 
• Deposition Author(s): Fedorov, A.A., Fedorov, E.V., Chan, K.K., Gerlt, J.A., Almo, S.C.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.50 Å
• R-Value Free: 0.201 
• R-Value Work: 0.186 
• R-Value Observed: 0.186 

Starting Model: experimental

Literature

Mechanism of the orotidine 5'-monophosphate decarboxylase-catalyzed reaction: evidence for substrate destabilization.

Chan, K.K., Wood, B.M., Fedorov, A.A., Fedorov, E.V., Imker, H.J., Amyes, T.L., Richard, J.P., Almo, S.C., Gerlt, J.A.

(2009) Biochemistry 48: 5518-5531

• PubMed: 19435314 
• DOI: https://doi.org/10.1021/bi900623r


• PubMed Abstract: 
  

  The reaction catalyzed by orotidine 5'-monophosphate decarboxylase (OMPDC) involves a stabilized anionic intermediate, although the structural basis for the rate acceleration (k(cat)/k(non), 7.1 x 10(16)) and proficiency [(k(cat)/K(M))/k(non), 4.8 x 10(22) M(-1)] is uncertain. That the OMPDCs from Methanothermobacter thermautotrophicus (MtOMPDC) and Saccharomyces cerevisiae (ScOMPDC) catalyze the exchange of H6 of the UMP product with solvent deuterium allows an estimate of a lower limit on the rate acceleration associated with stabilization of the intermediate and its flanking transition states (>or=10(10)). The origin of the "missing" contribution, or=10(10)), is of interest. Based on structures of liganded complexes, unfavorable electrostatic interactions between the substrate carboxylate group and a proximal Asp (Asp 70 in MtOMPDC and Asp 91 in ScOMPDC) have been proposed to contribute to the catalytic efficiency [Wu, N., Mo, Y., Gao, J., and Pai, E. F. (2000) Proc. Natl. Acad. Sci. U.S.A. 97, 2017-2022]. We investigated that hypothesis by structural and functional characterization of the D70N and D70G mutants of MtOMPDC and the D91N mutant of ScOMPDC. The substitutions for Asp 70 in MtOMPDC significantly decrease the value of k(cat) for decarboxylation of FOMP (a more reactive substrate analogue) but have little effect on the value of k(ex) for exchange of H6 of FUMP with solvent deuterium; the structures of wild-type MtOMPDC and its mutants are superimposable when complexed with 6-azaUMP. In contrast, the D91N mutant of ScOMPDC does not catalyze exchange of H6 of FUMP; the structures of wild-type ScOMPDC and its D91N mutant are not superimposable when complexed with 6-azaUMP, with differences in both the conformation of the active site loop and the orientation of the ligand vis a vis the active site residues. We propose that the differential effects of substitutions for Asp 70 of MtOMPDC on decarboxylation and exchange provide additional evidence for a carbanionic intermediate as well as the involvement of Asp 70 in substrate destabilization.

---

Organizational Affiliation: 

Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 50.42 kDa 
• Atom Count: 3,632 
• Modelled Residue Count: 435 
• Deposited Residue Count: 456 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Orotidine 5'-phosphate decarboxylase	A, B	228	Methanothermobacter thermautotrophicus str. Delta H	Mutation(s): 2  Gene Names: pyrF, MTH_129 EC: 4.1.1.23
UniProt
Find proteins for O26232 (Methanothermobacter thermautotrophicus (strain ATCC 29096 / DSM 1053 / JCM 10044 / NBRC 100330 / Delta H)) Explore O26232  Go to UniProtKB:  O26232

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
U5P	C [auth A], D [auth B]	URIDINE-5'-MONOPHOSPHATE C9 H13 N2 O9 P DJJCXFVJDGTHFX-XVFCMESISA-N

Binding Affinity Annotations
ID	Source	Binding Affinity
U	BindingDB:  3G22	Ki: 3.30e+5 (nM) from 1 assay(s)

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.50 Å
• R-Value Free: 0.201 
• R-Value Work: 0.186 
• R-Value Observed: 0.186 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 59.507	α = 90
b = 63.711	β = 114.94
c = 61.36	γ = 90

Software Package:

Software Name	Purpose
ADSC	data collection
BALBES	phasing
CNS	refinement
DENZO	data reduction
SCALEPACK	data scaling

Structure Validation

Entry History 

Deposition Data

• Released Date: 2009-06-23 
Deposition Author(s): Fedorov, A.A., Fedorov, E.V., Chan, K.K., Gerlt, J.A., Almo, S.C.

Revision History  

• Version 1.0: 2009-06-23
  Type: Initial release
  
• Version 1.1: 2011-07-13
  Changes: Version format compliance
• Version 1.2: 2021-10-20
  Changes: Database references, Derived calculations
• Version 1.3: 2023-09-06
  Changes: Data collection, Refinement description
• Version 2.0: 2024-10-16
  Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary