4IGD

Crystal structure of the zymogen catalytic region of Human MASP-1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.219 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Quantitative characterization of the activation steps of mannan-binding lectin (MBL)-associated serine proteases (MASPs) points to the central role of MASP-1 in the initiation of the complement lectin pathway

Megyeri, M.Harmat, V.Major, B.Vegh, A.Balczer, J.Heja, D.Szilagyi, K.Datz, D.Pal, G.Zavodszky, P.Gal, P.Dobo, J.

(2013) J.Biol.Chem. 288: 8922-8934

  • DOI: 10.1074/jbc.M112.446500

  • PubMed Abstract: 
  • Mannan-binding lectin (MBL)-associated serine proteases, MASP-1 and MASP-2, have been thought to autoactivate when MBL/ficolin·MASP complexes bind to pathogens triggering the complement lectin pathway. Autoactivation of MASPs occurs in two steps: 1) ...

    Mannan-binding lectin (MBL)-associated serine proteases, MASP-1 and MASP-2, have been thought to autoactivate when MBL/ficolin·MASP complexes bind to pathogens triggering the complement lectin pathway. Autoactivation of MASPs occurs in two steps: 1) zymogen autoactivation, when one proenzyme cleaves another proenzyme molecule of the same protease, and 2) autocatalytic activation, when the activated protease cleaves its own zymogen. Using recombinant catalytic fragments, we demonstrated that a stable proenzyme MASP-1 variant (R448Q) cleaved the inactive, catalytic site Ser-to-Ala variant (S646A). The autoactivation steps of MASP-1 were separately quantified using these mutants and the wild type enzyme. Analogous mutants were made for MASP-2, and rate constants of the autoactivation steps as well as the possible cross-activation steps between MASP-1 and MASP-2 were determined. Based on the rate constants, a kinetic model of lectin pathway activation was outlined. The zymogen autoactivation rate of MASP-1 is ∼3000-fold higher, and the autocatalytic activation of MASP-1 is about 140-fold faster than those of MASP-2. Moreover, both activated and proenzyme MASP-1 can effectively cleave proenzyme MASP-2. MASP-3, which does not autoactivate, is also cleaved by MASP-1 quite efficiently. The structure of the catalytic region of proenzyme MASP-1 R448Q was solved at 2.5 Å. Proenzyme MASP-1 R448Q readily cleaves synthetic substrates, and it is inhibited by a specific canonical inhibitor developed against active MASP-1, indicating that zymogen MASP-1 fluctuates between an inactive and an active-like conformation. The determined structure provides a feasible explanation for this phenomenon. In summary, autoactivation of MASP-1 is crucial for the activation of MBL/ficolin·MASP complexes, and in the proenzymic phase zymogen MASP-1 controls the process.


    Organizational Affiliation

    Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 29 Karolina Street, H-1113 Budapest, Hungary.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Mannan-binding lectin serine protease 1
A
406Homo sapiensMutation(s): 1 
Gene Names: MASP1 (CRARF, CRARF1, PRSS5)
EC: 3.4.21.-
Find proteins for P48740 (Homo sapiens)
Go to Gene View: MASP1
Go to UniProtKB:  P48740
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download SDF File 
Download CCD File 
A
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.219 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 63.310α = 90.00
b = 69.610β = 90.00
c = 117.680γ = 90.00
Software Package:
Software NamePurpose
XSCALEdata scaling
MxCuBEdata collection
XDSdata reduction
MOLREPphasing
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-02-13
    Type: Initial release
  • Version 1.1: 2013-07-10
    Type: Database references