4MDR

Crystal structure of adaptor protein complex 4 (AP-4) mu4 subunit C-terminal domain D190A mutant, in complex with a sorting peptide from the amyloid precursor protein (APP)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.216 

wwPDB Validation   3D Report Full Report



Literature

Structural and Functional Characterization of Cargo-Binding Sites on the mu 4-Subunit of Adaptor Protein Complex 4.

Ross, B.H.Lin, Y.Corales, E.A.Burgos, P.V.Mardones, G.A.

(2014) PLoS One 9: e88147-e88147

  • DOI: 10.1371/journal.pone.0088147
  • Primary Citation of Related Structures:  
    4MDR

  • PubMed Abstract: 
  • Adaptor protein (AP) complexes facilitate protein trafficking by playing key roles in the selection of cargo molecules to be sorted in post-Golgi compartments. Four AP complexes (AP-1 to AP-4) contain a medium-sized subunit (μ1-μ4) that recognizes YXXØ-s ...

    Adaptor protein (AP) complexes facilitate protein trafficking by playing key roles in the selection of cargo molecules to be sorted in post-Golgi compartments. Four AP complexes (AP-1 to AP-4) contain a medium-sized subunit (μ1-μ4) that recognizes YXXØ-sequences (Ø is a bulky hydrophobic residue), which are sorting signals in transmembrane proteins. A conserved, canonical region in μ subunits mediates recognition of YXXØ-signals by means of a critical aspartic acid. Recently we found that a non-canonical YXXØ-signal on the cytosolic tail of the Alzheimer's disease amyloid precursor protein (APP) binds to a distinct region of the μ4 subunit of the AP-4 complex. In this study we aimed to determine the functionality of both binding sites of μ4 on the recognition of the non-canonical YXXØ-signal of APP. We found that substitutions in either binding site abrogated the interaction with the APP-tail in yeast-two hybrid experiments. Further characterization by isothermal titration calorimetry showed instead loss of binding to the APP signal with only the substitution R283D at the non-canonical site, in contrast to a decrease in binding affinity with the substitution D190A at the canonical site. We solved the crystal structure of the C-terminal domain of the D190A mutant bound to this non-canonical YXXØ-signal. This structure showed no significant difference compared to that of wild-type μ4. Both differential scanning fluorimetry and limited proteolysis analyses demonstrated that the D190A substitution rendered μ4 less stable, suggesting an explanation for its lower binding affinity to the APP signal. Finally, in contrast to overexpression of the D190A mutant, and acting in a dominant-negative manner, overexpression of μ4 with either a F255A or a R283D substitution at the non-canonical site halted APP transport at the Golgi apparatus. Together, our analyses support that the functional recognition of the non-canonical YXXØ-signal of APP is limited to the non-canonical site of μ4.


    Organizational Affiliation

    Instituto de Fisiología, Facultad de Medicina, and Centro de Investigación Sur-Austral en Enfermedades del Sistema Nervioso, Universidad Austral de Chile, Valdivia, Chile.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
AP-4 complex subunit mu-1 A301Homo sapiensMutation(s): 3 
Gene Names: AP4M1MUARP2
Find proteins for O00189 (Homo sapiens)
Explore O00189 
Go to UniProtKB:  O00189
NIH Common Fund Data Resources
PHAROS:  O00189
Protein Feature View
Expand
  • Reference Sequence
  • Find similar proteins by:  Sequence   |   Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Amyloid beta A4 protein B10Homo sapiensMutation(s): 0 
Gene Names: APPA4AD1
Find proteins for P05067 (Homo sapiens)
Explore P05067 
Go to UniProtKB:  P05067
NIH Common Fund Data Resources
PHAROS:  P05067
Protein Feature View
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.216 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.507α = 90
b = 56.729β = 106.67
c = 60.18γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2014-03-12
    Type: Initial release