2KNV

NMR dimer structure of the UBA domain of p62 (SQSTM1)

Summary for 2KNV

• Entry DOI: 10.2210/pdb2knv/pdb
• Related: 2JY7 2K0B
• Descriptor: Sequestosome-1 (1 entity in total)
• Functional Keywords: ubiquitin binding, ubiquitin-associated domain, paget s disease of bone, helical bundle, dimer, protein binding
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: Q13501
• Total number of polymer chains: 2
• Total formula weight: 11488.81

Authors

Long, J.E.,Searle, M.S. (deposition date: 2009-09-04, release date: 2009-12-15, Last modification date: 2024-05-29)

Primary citation

Long, J.,Garner, T.P.,Pandya, M.J.,Craven, C.J.,Chen, P.,Shaw, B.,Williamson, M.P.,Layfield, R.,Searle, M.S.
Dimerisation of the UBA Domain of p62 Inhibits Ubiquitin Binding and Regulates NF-kappaB Signalling
J.Mol.Biol., 2009

PubMed Abstract: The ubiquitin (Ub)-binding p62 scaffold protein (encoded by the SQSTM1 gene) regulates a diverse range of signalling pathways leading to activation of the nuclear factor kappa B (NF-kappaB) family of transcription factors and is an important regulator of macroautophagy. Mutations within the gene encoding p62 are commonly found in patients with Paget's disease of bone and largely cluster within the C-terminal ubiquitin-associated (UBA) domain, impairing its ability to bind Ub, resulting in dysregulated NF-kappaB signalling. However, precisely how Ub-binding is regulated at the molecular level is unclear. NMR relaxation dispersion experiments, coupled with concentration-dependent NMR, CD, isothermal titration calorimetry and fluorescence kinetic measurements, reveal that the p62 UBA domain forms a highly stable dimer (K(dim) approximately 4-12 microM at 298 K). NMR analysis shows that the dimer interface partially occludes the Ub-binding surface, particularly at the C-terminus of helix 3, making UBA dimerisation and Ub-binding mutually exclusive processes. Somewhat unusually, the monomeric UBA appears to be the biologically active form and the dimer appears to be the inactive one. Engineered point mutations in loop 1 (E409K and G410K) are shown to destabilise the dimer interface, lead to a higher proportion of the bound monomer and, in NF-kappaB luciferase reporter assays, are associated with reduced NF-kappaB activity compared with wt-p62.

PubMed: 19931284
DOI: 10.1016/j.jmb.2009.11.032

Experimental method

SOLUTION NMR