8STW

K384N HUMAN CYSTATHIONINE BETA-SYNTHASE (delta 411-551)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.212 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.1 of the entry. See complete history


Literature

Disease-causing cystathionine beta-synthase linker mutations impair allosteric regulation.

Roman, J.V.Mascarenhas, R.Ceric, K.Ballou, D.P.Banerjee, R.

(2023) J Biol Chem 299: 105449-105449

  • DOI: https://doi.org/10.1016/j.jbc.2023.105449
  • Primary Citation of Related Structures:  
    8STW

  • PubMed Abstract: 

    Cystathionine β-synthase (CBS) catalyzes the committing step in the transsulfuration pathway, which is important for clearing homocysteine and furnishing cysteine. The transsulfuration pathway also generates H 2 S, a signaling molecule. CBS is a modular protein with a heme and pyridoxal phosphate-binding catalytic core, which is separated by a linker region from the C-terminal regulatory domain that binds S-adenosylmethionine (AdoMet), an allosteric activator. Recent cryo-EM structures reveal that CBS exists in a fibrillar form and undergoes a dramatic architectural rearrangement between the basal and AdoMet-bound states. CBS is the single most common locus of mutations associated with homocystinuria, and, in this study, we have characterized three clinical variants (K384E/N and M391I), which reside in the linker region. The native fibrillar form is destabilized in the variants, and differences in their limited proteolytic fingerprints also reveal conformational alterations. The crystal structure of the truncated K384N variant, lacking the regulatory domain, reveals that the overall fold of the catalytic core is unperturbed. M391I CBS exhibits a modest (1.4-fold) decrease while the K384E/N variants exhibit a significant (∼8-fold) decrease in basal activity, which is either unresponsive to or inhibited by AdoMet. Pre-steady state kinetic analyses reveal that the K384E/N substitutions exhibit pleiotropic effects and that the differences between them are expressed in the second half reaction, that is, homocysteine binding and reaction with the aminoacrylate intermediate. Together, these studies point to an important role for the linker in stabilizing the higher-order oligomeric structure of CBS and enabling AdoMet-dependent regulation.


  • Organizational Affiliation

    Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cystathionine beta-synthase, K384N variant
A, B, C, D, E
A, B, C, D, E, F
363Homo sapiensMutation(s): 1 
Gene Names: CBS
EC: 4.2.1.22
UniProt & NIH Common Fund Data Resources
Find proteins for P35520 (Homo sapiens)
Explore P35520 
Go to UniProtKB:  P35520
PHAROS:  P35520
GTEx:  ENSG00000160200 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP35520
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
HEM (Subject of Investigation/LOI)
Query on HEM

Download Ideal Coordinates CCD File 
H [auth A]
J [auth B]
L [auth C]
N [auth D]
P [auth E]
H [auth A],
J [auth B],
L [auth C],
N [auth D],
P [auth E],
R [auth F]
PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
PLP (Subject of Investigation/LOI)
Query on PLP

Download Ideal Coordinates CCD File 
G [auth A]
I [auth B]
K [auth C]
M [auth D]
O [auth E]
G [auth A],
I [auth B],
K [auth C],
M [auth D],
O [auth E],
Q [auth F]
PYRIDOXAL-5'-PHOSPHATE
C8 H10 N O6 P
NGVDGCNFYWLIFO-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.212 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 89.462α = 106.15
b = 90.189β = 105.49
c = 104.224γ = 107.47
Software Package:
Software NamePurpose
REFMACrefinement
DIALSdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM130183

Revision History  (Full details and data files)

  • Version 1.0: 2023-11-22
    Type: Initial release
  • Version 1.1: 2023-12-20
    Changes: Database references