4IP9

Structure of native human serum amyloid A1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.249 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural mechanism of serum amyloid A-mediated inflammatory amyloidosis.

Lu, J.Yu, Y.Zhu, I.Cheng, Y.Sun, P.D.

(2014) Proc.Natl.Acad.Sci.USA 111: 5189-5194

  • DOI: 10.1073/pnas.1322357111
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Serum amyloid A (SAA) represents an evolutionarily conserved family of inflammatory acute-phase proteins. It is also a major constituent of secondary amyloidosis. To understand its function and structural transition to amyloid, we determined a struct ...

    Serum amyloid A (SAA) represents an evolutionarily conserved family of inflammatory acute-phase proteins. It is also a major constituent of secondary amyloidosis. To understand its function and structural transition to amyloid, we determined a structure of human SAA1.1 in two crystal forms, representing a prototypic member of the family. Native SAA1.1 exists as a hexamer, with subunits displaying a unique four-helix bundle fold stabilized by its long C-terminal tail. Structure-based mutational studies revealed two positive-charge clusters, near the center and apex of the hexamer, that are involved in SAA association with heparin. The binding of high-density lipoprotein involves only the apex region of SAA and can be inhibited by heparin. Peptide amyloid formation assays identified the N-terminal helices 1 and 3 as amyloidogenic peptides of SAA1.1. Both peptides are secluded in the hexameric structure of SAA1.1, suggesting that the native SAA is nonpathogenic. Furthermore, dissociation of the SAA hexamer appears insufficient to initiate amyloidogenic transition, and proteolytic cleavage or removal of the C-terminal tail of SAA resulted in formation of various-sized structural aggregates containing ∼5-nm regular repeating protofibril-like units. The combined structural and functional studies provide mechanistic insights into the pathogenic contribution of glycosaminoglycan in SAA1.1-mediated AA amyloid formation.


    Organizational Affiliation

    Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Serum amyloid A-1 protein
A, B
111Homo sapiensMutation(s): 0 
Gene Names: SAA1
Find proteins for P0DJI8 (Homo sapiens)
Go to Gene View: SAA1
Go to UniProtKB:  P0DJI8
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
P4C
Query on P4C

Download SDF File 
Download CCD File 
A, B
O-ACETALDEHYDYL-HEXAETHYLENE GLYCOL
POLYETHYLENE 400
C14 H28 O8
CTLLATPOKUEFSQ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.249 
  • Space Group: H 3 2
Unit Cell:
Length (Å)Angle (°)
a = 93.850α = 90.00
b = 93.850β = 90.00
c = 130.520γ = 120.00
Software Package:
Software NamePurpose
HKL-2000data reduction
PHASERphasing
HKL-2000data scaling
HKL-2000data collection
BUSTERrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2013-01-09 
  • Released Date: 2014-03-26 
  • Deposition Author(s): Lu, J., Sun, P.D.

Revision History 

  • Version 1.0: 2014-03-26
    Type: Initial release
  • Version 1.1: 2014-05-14
    Type: Database references
  • Version 1.2: 2018-01-24
    Type: Structure summary