Crystal Structure of the Fluoroacetate Dehalogenase RPA1163 - Tyr219Phe - Chloroacetate soaked 2hr

Experimental Data Snapshot

  • Resolution: 1.51 Å
  • R-Value Free: 0.202 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.175 

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Substrate-Based Allosteric Regulation of a Homodimeric Enzyme.

Mehrabi, P.Di Pietrantonio, C.Kim, T.H.Sljoka, A.Taverner, K.Ing, C.Kruglyak, N.Pomes, R.Pai, E.F.Prosser, R.S.

(2019) J Am Chem Soc 141: 11540-11556

  • DOI: https://doi.org/10.1021/jacs.9b03703
  • Primary Citation of Related Structures:  
    6QKS, 6QKT, 6QKU, 6QKW

  • PubMed Abstract: 

    Many enzymes operate through half-of-the sites reactivity wherein a single protomer is catalytically engaged at one time. In the case of the homodimeric enzyme, fluoroacetate dehalogenase, substrate binding triggers closing of a regulatory cap domain in the empty protomer, preventing substrate access to the remaining active site. However, the empty protomer serves a critical role by acquiring more disorder upon substrate binding, thereby entropically favoring the forward reaction. Empty protomer dynamics are also allosterically coupled to the bound protomer, driving conformational exchange at the active site and progress along the reaction coordinate. Here, we show that at high concentrations, a second substrate binds along the substrate-access channel of the occupied protomer, thereby dampening interprotomer dynamics and inhibiting catalysis. While a mutation (K152I) abrogates second site binding and removes inhibitory effects, it also precipitously lowers the maximum catalytic rate, implying a role for the allosteric pocket at low substrate concentrations, where only a single substrate engages the enzyme at one time. We show that this outer pocket first desolvates the substrate, whereupon it is deposited in the active site. Substrate binding to the active site then triggers the empty outer pocket to serve as an interprotomer allosteric conduit, enabling enhanced dynamics and sampling of activation states needed for catalysis. These allosteric networks and the ensuing changes resulting from second substrate binding are delineated using rigidity-based allosteric transmission theory and validated by nuclear magnetic resonance and functional studies. The results illustrate the role of dynamics along allosteric networks in facilitating function.

  • Organizational Affiliation

    Department of Medical Biophysics , University of Toronto , Toronto , Ontario M5G 1L7 , Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Fluoroacetate dehalogenase
A, B
306Rhodopseudomonas palustrisMutation(s): 0 
Gene Names: RPYSC3_11920
Find proteins for Q6NAM1 (Rhodopseudomonas palustris (strain ATCC BAA-98 / CGA009))
Explore Q6NAM1 
Go to UniProtKB:  Q6NAM1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6NAM1
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.51 Å
  • R-Value Free: 0.202 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.175 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 41.83α = 90
b = 79.55β = 103.31
c = 84.98γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2019-06-26
    Type: Initial release
  • Version 1.1: 2019-07-31
    Changes: Data collection, Database references
  • Version 1.2: 2019-09-25
    Changes: Data collection, Database references, Source and taxonomy, Structure summary
  • Version 2.0: 2023-11-15
    Changes: Atomic model, Data collection, Database references