title: Rapid determination of protein solubility and stability conditions for NMR studies using incomplete factorial design.
abstract: Sample preparation constitutes a crucial and limiting step in structural studies of proteins by NMR. The determination of the solubility and stability (SAS) conditions of biomolecules at millimolar concentrations stays today empirical and hence time- and material-consuming. Only few studies have been recently done in this field and they have highlighted the interest of using crystallogenesis tools to optimise sample conditions. In this study, we have adapted a method based on incomplete factorial design and making use of crystallisation plates to quantify the influence of physico-chemical parameters such as buffer pH and salts on protein SAS. A description of the experimental set up and an evaluation of the method are given by case studies on two functional domains from the bacterial regulatory protein LicT as well as two other proteins. Using this method, we could rapidly determine optimised conditions for extracting soluble proteins from bacterial cells and for preparing purified protein samples sufficiently concentrated and stable for NMR characterisation. The drastic reduction in the time and number of experiments required for searching protein SAS conditions makes this method particularly well-adapted for a systematic investigation on a large range of physico-chemical parameters.
authors.affiliation: Centre de Biochimie Structurale, CNRS UMR 5048/INSERM UMR 554/Universito de Montpellier 1, 29 rue de Navacelles, 34090, Montpellier Cedex, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Ducat
authors.forename: Nathalie
authors.initials: N
authors.lastname: Declerck
authors.forename: Thierry
authors.initials: T
authors.lastname: Gostan
authors.forename: Michel
authors.initials: M
authors.lastname: Kochoyan
authors.forename: Hélène
authors.initials: H
authors.lastname: Déméné
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011506:Proteins / Q000737:chemistry*; D012107:Research Design; D012995:Solubility; D014157:Transcription Factors / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; C098955:LicT protein, Bacteria; D011506:Proteins; D014157:Transcription Factors