5HV9

Human LTC4S mutant-S36E


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.289 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Phosphorylation of Leukotriene C4 Synthase at Serine 36 Impairs Catalytic Activity.

Ahmad, S.Ytterberg, A.J.Thulasingam, M.Tholander, F.Bergman, T.Zubarev, R.Wetterholm, A.Rinaldo-Matthis, A.Haeggstrom, J.Z.

(2016) J.Biol.Chem. 291: 18410-18418

  • DOI: 10.1074/jbc.M116.735647

  • PubMed Abstract: 
  • Leukotriene C4 synthase (LTC4S) catalyzes the formation of the proinflammatory lipid mediator leukotriene C4 (LTC4). LTC4 is the parent molecule of the cysteinyl leukotrienes, which are recognized for their pathogenic role in asthma and allergic dise ...

    Leukotriene C4 synthase (LTC4S) catalyzes the formation of the proinflammatory lipid mediator leukotriene C4 (LTC4). LTC4 is the parent molecule of the cysteinyl leukotrienes, which are recognized for their pathogenic role in asthma and allergic diseases. Cellular LTC4S activity is suppressed by PKC-mediated phosphorylation, and recently a downstream p70S6k was shown to play an important role in this process. Here, we identified Ser(36) as the major p70S6k phosphorylation site, along with a low frequency site at Thr(40), using an in vitro phosphorylation assay combined with mass spectrometry. The functional consequences of p70S6k phosphorylation were tested with the phosphomimetic mutant S36E, which displayed only about 20% (20 μmol/min/mg) of the activity of WT enzyme (95 μmol/min/mg), whereas the enzyme activity of T40E was not significantly affected. The enzyme activity of S36E increased linearly with increasing LTA4 concentrations during the steady-state kinetics analysis, indicating poor lipid substrate binding. The Ser(36) is located in a loop region close to the entrance of the proposed substrate binding pocket. Comparative molecular dynamics indicated that Ser(36) upon phosphorylation will pull the first luminal loop of LTC4S toward the neighboring subunit of the functional homotrimer, thereby forming hydrogen bonds with Arg(104) in the adjacent subunit. Because Arg(104) is a key catalytic residue responsible for stabilization of the glutathione thiolate anion, this phosphorylation-induced interaction leads to a reduction of the catalytic activity. In addition, the positional shift of the loop and its interaction with the neighboring subunit affect active site access. Thus, our mutational and kinetic data, together with molecular simulations, suggest that phosphorylation of Ser(36) inhibits the catalytic function of LTC4S by interference with the catalytic machinery.


    Organizational Affiliation

    From the Divisions of Chemistry II.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Leukotriene C4 synthase
A
156Homo 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 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
GSH
Query on GSH

Download SDF File 
Download CCD File 
A
GLUTATHIONE
C10 H17 N3 O6 S
RWSXRVCMGQZWBV-WDSKDSINSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.289 
  • Space Group: F 2 3
Unit Cell:
Length (Å)Angle (°)
a = 168.042α = 90.00
b = 168.042β = 90.00
c = 168.042γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
XDSdata reduction
REFMACrefinement
XDSdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Swedish Research CouncilSweden--

Revision History 

  • Version 1.0: 2016-07-13
    Type: Initial release
  • Version 1.1: 2016-07-20
    Type: Database references
  • Version 1.2: 2016-09-07
    Type: Database references
  • Version 1.3: 2017-09-13
    Type: Advisory, Author supporting evidence