title: The disordered amino-terminus of SIMPL interacts with members of the 70-kDa heat-shock protein family.
abstract: The p65 coactivator SIMPL is a small protein that lacks any conserved domains of known function. To better understand regulation of SIMPL activity, we sought to identify novel SIMPL interacting proteins using mass spectrometry analysis of SIMPL containing complexes. Two members of the 70-kDa heat-shock protein family, Hsp70 and Hsc70, were identified as SIMPL binding proteins. Subsequent immunocomplexing assays confirmed this interaction and demonstrated that the amino-terminus of SIMPL is required for this interaction. Using a combination of amino acid composition analysis, PONDR VL-XT prediction, charge-hydropathy plots, and cumulative distribution functions, the amino-terminal region of both mouse and human SIMPL proteins was predicted to be intrinsically disordered. These data, taken together, suggest that Hsp70/Hsc70 bind the intrinsically disordered amino-terminal region of SIMPL to stabilize the protein and thereby regulate its activity. Understanding the regulation of SIMPL through its interaction with Hsp70/Hsc70 may serve as a novel means of modulating tumor necrosis factor alpha signaling.
authors.affiliation: Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indiana University Cancer Center, Indianapolis, Indiana 46220, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Haag Breese
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Uversky
authors.forename: Millie M
authors.initials: MM
authors.lastname: Georgiadis
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Harrington
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D002478:Cells, Cultured; D019295:Computational Biology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D013058:Mass Spectrometry; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D050505:Mutant Proteins; C493527:SIMPL protein, mouse