Arc is a flexible modular protein capable of reversible self-oligomerization.
The immediate early gene product Arc (activity-regulated cytoskeleton-associated protein) is posited as a master regulator of long-term synaptic plasticity and memory. However, the physicochemical and structural properties of Arc have not been elucidated. In the present study, we expressed and purified recombinant human Arc (hArc) and performed the first biochemical and biophysical analysis of hArc's structure and stability. Limited proteolysis assays and MS analysis indicate that hArc has two major domains on either side of a central more disordered linker region, consistent with in silico structure predictions. hArc's secondary structure was estimated using CD, and stability was analysed by CD-monitored thermal denaturation and differential scanning fluorimetry (DSF). Oligomerization states under different conditions were studied by dynamic light scattering (DLS) and visualized by AFM and EM. Biophysical analyses show that hArc is a modular protein with defined secondary structure and loose tertiary structure. hArc appears to be pyramid-shaped as a monomer and is capable of reversible self-association, forming large soluble oligomers. The N-terminal domain of hArc is highly basic, which may promote interaction with cytoskeletal structures or other polyanionic surfaces, whereas the C-terminal domain is acidic and stabilized by ionic conditions that promote oligomerization. Upon binding of presenilin-1 (PS1) peptide, hArc undergoes a large structural change. A non-synonymous genetic variant of hArc (V231G) showed properties similar to the wild-type (WT) protein. We conclude that hArc is a flexible multi-domain protein that exists in monomeric and oligomeric forms, compatible with a diverse, hub-like role in plasticity-related processes.
*Dr Einar Martens' Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, 5009 Bergen, Norway.
Craig
C
Myrum
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Anne
A
Baumann
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Helene J
HJ
Bustad
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Marte Innselset
MI
Flydal
§European Molecular Biology Laboratory, Grenoble Outstation, 72 rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
Vincent
V
Mariaule
║Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
Sara
S
Alvira
║Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
Jorge
J
Cuéllar
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Jan
J
Haavik
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Jonathan
J
Soulé
║Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
José Maria
JM
Valpuesta
§European Molecular Biology Laboratory, Grenoble Outstation, 72 rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France.
José Antonio
JA
Márquez
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Aurora
A
Martinez
†Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway.
Clive R
CR
Bramham
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D055592:Biophysical Phenomena; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D014644:Genetic Variation; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D053764:Presenilin-1 / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1; D011994:Recombinant Proteins; C092069:activity regulated cytoskeletal-associated protein