title: Quinary structure modulates protein stability in cells.
abstract: Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein-matrix contacts that comprise quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions. We use NMR-detected H/D exchange to quantify quinary interactions between the B1 domain of protein G and the cytosol of Escherichia coli. We demonstrate that a surface mutation in this protein is 10-fold more destabilizing in cells than in buffer, a surprising result that firmly establishes the significance of quinary interactions. Remarkably, the energy involved in these interactions can be as large as the energies that stabilize specific protein complexes. These results will drive the critical task of implementing quinary structure into models for understanding the proteome.
authors.affiliation: Departments of Chemistry and.
authors.forename: William B
authors.initials: WB
authors.lastname: Monteith
authors.affiliation: Departments of Chemistry and.
authors.forename: Rachel D
authors.initials: RD
authors.lastname: Cohen
authors.affiliation: Departments of Chemistry and.
authors.forename: Austin E
authors.initials: AE
authors.lastname: Smith
authors.affiliation: Departments of Chemistry and.
authors.forename: Emilio
authors.initials: E
authors.lastname: Guzman-Cisneros
authors.affiliation: Departments of Chemistry and Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 gary_pielak@unc.edu.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Pielak
mesh_terms: D017931:DNA Primers / Q000235:genetics; D041961:Deuterium Exchange Measurement; D004926:Escherichia coli; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D010957:Plasmids / Q000235:genetics; D011487:Protein Conformation; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification; D055550:Protein Stability; D018080:Receptors, GABA-B / Q000737:chemistry* / Q000302:isolation & purification; D013816:Thermodynamics
chemical_list: D017931:DNA Primers; D009587:Nitrogen Isotopes; D020033:Protein Isoforms; D018080:Receptors, GABA-B
keywords: H/D exchange; protein NMR; protein thermodynamics; quinary interactions