title: Decrease in pH destabilizes individual vault nanocages by weakening the inter-protein lateral interaction.
abstract: Vault particles are naturally occurring proteinaceous cages with promising application as molecular containers. The use of vaults as functional transporters requires a profound understanding of their structural stability to guarantee the protection and controlled payload delivery. Previous results performed with bulk techniques or at non-physiological conditions have suggested pH as a parameter to control vault dynamics. Here we use Atomic Force Microscopy (AFM) to monitor the structural evolution of individual vault particles while changing the pH in real time. Our experiments show that decreasing the pH of the solution destabilize the barrel region, the central part of vault particles, and leads to the aggregation of the cages. Additional analyses using Quartz-Crystal Microbalance (QCM) and Differential Scanning Fluorimetry (DSF) are consistent with our single molecule AFM experiments. The observed topographical defects suggest that low pH weakens the bonds between adjacent proteins. We hypothesize that the observed effects are related to the strong polar character of the protein-protein lateral interactions. Overall, our study unveils the mechanism for the influence of a biologically relevant range of pHs on the stability and dynamics of vault particles.
authors.affiliation: Departamento de Física de la Materia Condensada, UAM, Francisco Tomás y Valiente 7, 28049-Madrid, Spain.
authors.forename: Aida
authors.initials: A
authors.lastname: Llauró
authors.affiliation: Structural Biology Unit, Institut de Biologia Molecular de Barcelona, CSIC. Baldiri I Reixac 10, 08028-Barcelona, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Guerra
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Kant
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Bothner
authors.affiliation: Structural Biology Unit, Institut de Biologia Molecular de Barcelona, CSIC. Baldiri I Reixac 10, 08028-Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Verdaguer
authors.affiliation: Departamento de Física de la Materia Condensada, UAM, Francisco Tomás y Valiente 7, 28049-Madrid, Spain.|Condensed Matter Physics Center IFIMAC UAM, Francisco Tomás y Valiente 7, 28049-Madrid, Spain.
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: de Pablo
mesh_terms: D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force / Q000379:methods*; D008958:Models, Molecular; D036103:Nanotechnology; D055550:Protein Stability; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods*; D020394:Vault Ribonucleoprotein Particles / Q000737:chemistry*
chemical_list: D020394:Vault Ribonucleoprotein Particles