4PYA

MoaC K51A in complex with 3',8-cH2GTP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.79 Å
  • R-Value Free: 0.194 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 

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Ligand Structure Quality Assessment 


This is version 1.4 of the entry. See complete history


Literature

Mechanism of pyranopterin ring formation in molybdenum cofactor biosynthesis.

Hover, B.M.Tonthat, N.K.Schumacher, M.A.Yokoyama, K.

(2015) Proc Natl Acad Sci U S A 112: 6347-6352

  • DOI: 10.1073/pnas.1500697112
  • Primary Citation of Related Structures:  
    4PYA, 4PYD

  • PubMed Abstract: 
  • The molybdenum cofactor (Moco) is essential for all kingdoms of life, plays central roles in various biological processes, and must be biosynthesized de novo. During Moco biosynthesis, the characteristic pyranopterin ring is constructed by a complex rearrangement of guanosine 5'-triphosphate (GTP) into cyclic pyranopterin (cPMP) through the action of two enzymes, MoaA and MoaC (molybdenum cofactor biosynthesis protein A and C, respectively) ...

    The molybdenum cofactor (Moco) is essential for all kingdoms of life, plays central roles in various biological processes, and must be biosynthesized de novo. During Moco biosynthesis, the characteristic pyranopterin ring is constructed by a complex rearrangement of guanosine 5'-triphosphate (GTP) into cyclic pyranopterin (cPMP) through the action of two enzymes, MoaA and MoaC (molybdenum cofactor biosynthesis protein A and C, respectively). Conventionally, MoaA was considered to catalyze the majority of this transformation, with MoaC playing little or no role in the pyranopterin formation. Recently, this view was challenged by the isolation of 3',8-cyclo-7,8-dihydro-guanosine 5'-triphosphate (3',8-cH2GTP) as the product of in vitro MoaA reactions. To elucidate the mechanism of formation of Moco pyranopterin backbone, we performed biochemical characterization of 3',8-cH2GTP and functional and X-ray crystallographic characterizations of MoaC. These studies revealed that 3',8-cH2GTP is the only product of MoaA that can be converted to cPMP by MoaC. Our structural studies captured the specific binding of 3',8-cH2GTP in the active site of MoaC. These observations provided strong evidence that the physiological function of MoaA is the conversion of GTP to 3',8-cH2GTP (GTP 3',8-cyclase), and that of MoaC is to catalyze the rearrangement of 3',8-cH2GTP into cPMP (cPMP synthase). Furthermore, our structure-guided studies suggest that MoaC catalysis involves the dynamic motions of enzyme active-site loops as a way to control the timing of interaction between the reaction intermediates and catalytically essential amino acid residues. Thus, these results reveal the previously unidentified mechanism behind Moco biosynthesis and provide mechanistic and structural insights into how enzymes catalyze complex rearrangement reactions.


    Organizational Affiliation

    Department of Biochemistry, Duke University Medical Center, Durham, NC 27710 ken.yoko@duke.edu maria.schumacher@duke.edu.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Molybdenum cofactor biosynthesis protein MoaCA161Escherichia coli K-12Mutation(s): 2 
Gene Names: moaCchlA3b0783JW0766
EC: 4.6.1.17
UniProt
Find proteins for P0A738 (Escherichia coli (strain K12))
Explore P0A738 
Go to UniProtKB:  P0A738
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.79 Å
  • R-Value Free: 0.194 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 
  • Space Group: P 63 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 89.933α = 90
b = 89.933β = 90
c = 62.446γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PHENIXrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment  



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-04-29
    Type: Initial release
  • Version 1.1: 2015-05-06
    Changes: Database references
  • Version 1.2: 2015-06-03
    Changes: Database references
  • Version 1.3: 2017-11-22
    Changes: Refinement description
  • Version 1.4: 2018-08-29
    Changes: Data collection, Source and taxonomy, Structure summary