6AM8

Engineered tryptophan synthase b-subunit from Pyrococcus furiosus, PfTrpB2B9 with Trp bound as E(Aex2)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.83 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.203 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Directed Evolution Mimics Allosteric Activation by Stepwise Tuning of the Conformational Ensemble.

Buller, A.R.van Roye, P.Cahn, J.K.B.Scheele, R.A.Herger, M.Arnold, F.H.

(2018) J Am Chem Soc 140: 7256-7266

  • DOI: 10.1021/jacs.8b03490
  • Primary Citation of Related Structures:  
    6AM7, 6AM9, 6AM8, 6AMC, 6AMI, 6AMH, 5VM5

  • PubMed Abstract: 
  • Allosteric enzymes contain a wealth of catalytic diversity that remains distinctly underutilized for biocatalysis. Tryptophan synthase is a model allosteric system and a valuable enzyme for the synthesis of noncanonical amino acids (ncAA). Previously, we evolved the β-subunit from Pyrococcus furiosus, PfTrpB, for ncAA synthase activity in the absence of its native partner protein PfTrpA ...

    Allosteric enzymes contain a wealth of catalytic diversity that remains distinctly underutilized for biocatalysis. Tryptophan synthase is a model allosteric system and a valuable enzyme for the synthesis of noncanonical amino acids (ncAA). Previously, we evolved the β-subunit from Pyrococcus furiosus, PfTrpB, for ncAA synthase activity in the absence of its native partner protein PfTrpA. However, the precise mechanism by which mutation activated TrpB to afford a stand-alone catalyst remained enigmatic. Here, we show that directed evolution caused a gradual change in the rate-limiting step of the catalytic cycle. Concomitantly, the steady-state distribution of the intermediates shifts to favor covalently bound Trp adducts, which have increased thermodynamic stability. The biochemical properties of these evolved, stand-alone TrpBs converge on those induced in the native system by allosteric activation. High-resolution crystal structures of the wild-type enzyme, an intermediate in the lineage, and the final variant, encompassing five distinct chemical states, show that activating mutations have only minor structural effects on their immediate environment. Instead, mutation stabilizes the large-scale motion of a subdomain to favor an otherwise transiently populated closed conformational state. This increase in stability enabled the first structural description of Trp covalently bound in a catalytically active TrpB, confirming key features of catalysis. These data combine to show that sophisticated models of allostery are not a prerequisite to recapitulating its complex effects via directed evolution, opening the way to engineering stand-alone versions of diverse allosteric enzymes.


    Organizational Affiliation

    Division of Chemistry and Chemical Engineering , California Institute of Technology , 210-41, 1200 East California Boulevard , Pasadena , California 91125 , United States.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Tryptophan synthase beta chain 1A, D396Pyrococcus furiosus DSM 3638Mutation(s): 8 
Gene Names: trpB1PF1706
EC: 4.2.1.20
UniProt
Find proteins for Q8U093 (Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1))
Explore Q8U093 
Go to UniProtKB:  Q8U093
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Tryptophan synthase beta chain 1B, C396Pyrococcus furiosus DSM 3638Mutation(s): 8 
Gene Names: trpB1PF1706
EC: 4.2.1.20
UniProt
Find proteins for Q8U093 (Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1))
Explore Q8U093 
Go to UniProtKB:  Q8U093
Protein Feature View
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  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
LLP
Query on LLP
A, DL-PEPTIDE LINKINGC14 H22 N3 O7 PLYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.83 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.203 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 82.233α = 90
b = 106.036β = 90
c = 158.709γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
XDSdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2018-05-16
    Type: Initial release
  • Version 1.1: 2018-06-20
    Changes: Data collection, Database references