3LEO

Structure of human Leukotriene C4 synthase mutant R31Q in complex with glutathione


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.196 
  • R-Value Work: 0.172 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Arginine 104 is a key catalytic residue in leukotriene C4 synthase.

Rinaldo-Matthis, A.Wetterholm, A.Martinez Molina, D.Holm, J.Niegowski, D.Ohlson, E.Nordlund, P.Morgenstern, R.Haeggstrom, J.Z.

(2010) J.Biol.Chem. 285: 40771-40776

  • DOI: 10.1074/jbc.M110.105940

  • PubMed Abstract: 
  • Human leukotriene C(4) synthase (hLTC(4)S) is an integral membrane enzyme that conjugates leukotriene (LT) A(4) with glutathione to form LTC(4), a precursor to the cysteinyl leukotrienes (LTC(4), LTD(4), and LTE(4)) that are involved in the pathogene ...

    Human leukotriene C(4) synthase (hLTC(4)S) is an integral membrane enzyme that conjugates leukotriene (LT) A(4) with glutathione to form LTC(4), a precursor to the cysteinyl leukotrienes (LTC(4), LTD(4), and LTE(4)) that are involved in the pathogenesis of human bronchial asthma. From the crystal structure of hLTC(4)S, Arg-104 and Arg-31 have been implicated in the conjugation reaction. Here, we used site-directed mutagenesis, UV spectroscopy, and x-ray crystallography to examine the catalytic role of Arg-104 and Arg-31. Exchange of Arg-104 with Ala, Ser, Thr, or Lys abolished 94.3-99.9% of the specific activity against LTA(4). Steady-state kinetics of R104A and R104S revealed that the K(m) for GSH was not significantly affected. UV difference spectra of the binary enzyme-GSH complex indicated that GSH ionization depends on the presence of Arg-104 because no thiolate signal, with λ(max) at 239 nm, could be detected using R104A or R104S hLTC(4)S. Apparently, the interaction of Arg-104 with the thiol group of GSH reduces its pK(a) to allow formation of a thiolate anion and subsequent nucleophilic attack at C6 of LTA(4). On the other hand, exchange of Arg-31 with Ala or Glu reduced the catalytic activity of hLTC(4)S by 88 and 70%, respectively, without significantly affecting the k(cat)/K(m) values for GSH, and a crystal structure of R31Q hLTC(4)S (2.1 Å) revealed a Gln-31 side chain pointing away from the active site. We conclude that Arg-104 plays a critical role in the catalytic mechanism of hLTC(4)S, whereas a functional role of Arg-31 seems more elusive. Because Arg-104 is a conserved residue, our results pertain to other homologous membrane proteins and represent a structure-function paradigm probably common to all microsomal GSH transferases.


    Organizational Affiliation

    Division of Chemistry 2, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Leukotriene C4 synthase
A
155Homo sapiensMutation(s): 1 
Gene Names: LTC4S
EC: 4.4.1.20
Find proteins for Q16873 (Homo sapiens)
Go to Gene View: LTC4S
Go to UniProtKB:  Q16873
Small Molecules
Ligands 7 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

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A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
GOL
Query on GOL

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A
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
GSH
Query on GSH

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A
GLUTATHIONE
C10 H17 N3 O6 S
RWSXRVCMGQZWBV-WDSKDSINSA-N
 Ligand Interaction
PAM
Query on PAM

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A
PALMITOLEIC ACID
C16 H30 O2
SECPZKHBENQXJG-FPLPWBNLSA-N
 Ligand Interaction
LMT
Query on LMT

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A
DODECYL-BETA-D-MALTOSIDE
C24 H46 O11
NLEBIOOXCVAHBD-QKMCSOCLSA-N
 Ligand Interaction
NI
Query on NI

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A
NICKEL (II) ION
Ni
VEQPNABPJHWNSG-UHFFFAOYSA-N
 Ligand Interaction
PLM
Query on PLM

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A
PALMITIC ACID
C16 H32 O2
IPCSVZSSVZVIGE-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.196 
  • R-Value Work: 0.172 
  • Space Group: F 2 3
Unit Cell:
Length (Å)Angle (°)
a = 169.540α = 90.00
b = 169.540β = 90.00
c = 169.540γ = 90.00
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
XDSdata reduction
REFMACrefinement
ADSCdata collection
PHASERphasing
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-10-27
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2012-03-21
    Type: Non-polymer description
  • Version 1.3: 2012-12-26
    Type: Database references