title: Getting the best out of long-wavelength X-rays: de novo chlorine/sulfur SAD phasing of a structural protein from ATV.
abstract: The structure of a 14 kDa structural protein from Acidianus two-tailed virus (ATV) was solved by single-wavelength anomalous diffraction (SAD) phasing using X-ray data collected at 2.0 A wavelength. Although the anomalous signal from methionine sulfurs was expected to suffice to solve the structure, one chloride ion turned out to be essential to achieve phasing. The minimal data requirements and the relative contributions of the Cl and S atoms to phasing are discussed. This work supports the feasibility of a systematic approach for the solution of protein crystal structures by SAD based on intrinsic protein light atoms along with associated chloride ions from the solvent. In such cases, data collection at long wavelengths may be a time-efficient alternative to selenomethionine substitution and heavy-atom derivatization.
authors.affiliation: Architecture et Fonction des Macromolécules Biologiques UMR 6098, CNRS, Universités d'Aix-Marseille I et II, Case 932, 163 Avenue de Luminy, 13288 Marseille CEDEX 9, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Goulet
authors.forename: Gisle
authors.initials: G
authors.lastname: Vestergaard
authors.forename: Catarina
authors.initials: C
authors.lastname: Felisberto-Rodrigues
authors.forename: Valérie
authors.initials: V
authors.lastname: Campanacci
authors.forename: Roger A
authors.initials: RA
authors.lastname: Garrett
authors.forename: Christian
authors.initials: C
authors.lastname: Cambillau
authors.forename: Miguel
authors.initials: M
authors.lastname: Ortiz-Lombardía
mesh_terms: D041541:Acidianus / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D012645:Selenomethionine / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry*; D015678:Viral Structural Proteins / Q000032:analysis* / Q000737:chemistry; D014965:X-Rays
chemical_list: D015678:Viral Structural Proteins; D002713:Chlorine; D013455:Sulfur; D012645:Selenomethionine