4BB2

Crystal structure of cleaved corticosteroid-binding globulin in complex with progesterone


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.177 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Corticosteroid-Binding Globulin: Structure-Function Implications from Species Differences

Gardill, B.R.Vogl, M.R.Lin, H.Hammond, G.L.Muller, Y.A.

(2012) Plos One 7: 52759

  • DOI: 10.1371/journal.pone.0052759

  • PubMed Abstract: 
  • Corticosteroid-binding globulin (CBG) transports glucocorticoids and progesterone in the blood and thereby modulates the tissue availability of these hormones. As a member of the serine protease inhibitor (SERPIN) family, CBG displays a reactive cent ...

    Corticosteroid-binding globulin (CBG) transports glucocorticoids and progesterone in the blood and thereby modulates the tissue availability of these hormones. As a member of the serine protease inhibitor (SERPIN) family, CBG displays a reactive center loop (RCL) that is targeted by proteinases. Cleavage of the RCL is thought to trigger a SERPIN-typical stressed-to-relaxed (S-to-R) transition that leads to marked structural rearrangements and a reduced steroid-binding affinity. To characterize structure-function relationships in CBG we studied various conformational states of E. coli-produced rat and human CBG. In the 2.5 Å crystal structure of human CBG in complex with progesterone, the RCL is cleaved at a novel site that differs from the known human neutrophil elastase recognition site. Although the cleaved RCL segment is five residues longer than anticipated, it becomes an integral part of β-sheet A as a result of the S-to-R transition. The atomic interactions observed between progesterone and CBG explain the lower affinity of progesterone in comparison to corticosteroids. Surprisingly, CD measurements in combination with thermal unfolding experiments show that rat CBG fails to undergo an S-to-R transition upon proteolytic cleavage of the RCL hinting that the S-to-R transition observed in human CBG is not a prerequisite for CBG function in rat. This observation cautions against drawing general conclusions about molecular mechanisms by comparing and merging structural data from different species.


    Organizational Affiliation

    Department of Biology, Lehrstuhl für Biotechnik, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CORTICOSTEROID-BINDING GLOBULIN
A
340Homo sapiensMutation(s): 1 
Gene Names: SERPINA6 (CBG)
Find proteins for P08185 (Homo sapiens)
Go to Gene View: SERPINA6
Go to UniProtKB:  P08185
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
CORTICOSTEROID-BINDING GLOBULIN
B
34Homo sapiensMutation(s): 0 
Gene Names: SERPINA6 (CBG)
Find proteins for P08185 (Homo sapiens)
Go to Gene View: SERPINA6
Go to UniProtKB:  P08185
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EDO
Query on EDO

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Download CCD File 
A
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
STR
Query on STR

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Download CCD File 
B
PROGESTERONE
C21 H30 O2
RJKFOVLPORLFTN-LEKSSAKUSA-N
 Ligand Interaction
CYS
Query on CYS

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Download CCD File 
A
CYSTEINE
C3 H7 N O2 S
XUJNEKJLAYXESH-REOHCLBHSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
STRKd: 85 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.177 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 89.190α = 90.00
b = 122.700β = 90.00
c = 81.930γ = 90.00
Software Package:
Software NamePurpose
XSCALEdata scaling
REFMACrefinement
XDSdata reduction
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-12-26
    Type: Initial release
  • Version 1.1: 2013-01-23
    Type: Database references