Direct phasing at low resolution of a protein copurified with human paraoxonase (PON1).
In this paper, the low-resolution structure of a previously unknown protein copurified with human paraoxonase (PON1) is reported. The structure of this protein was very difficult to solve using classical crystallographic methods. Progress was made using a new phasing method based on topological analysis. From the experimental point of view, this method has the advantage of requiring only a simple low-resolution X-ray data set. The program used and the different steps of the data-processing and phasing procedure are described. The results provided an insight into the failure of previous molecular-replacement attempts. The low-resolution shape of the protein which was presented with confidence is compared with and confirmed by the structure at 1.8 A solved subsequently using classical methods. This work shows that this direct-phasing method could be used systematically in difficult cases: it provides low-resolution structural information comparable with that obtainable by electron microscopy.
Fokine
A
A
Laboratoire de Cristallographie et Modélisation des Matériaux Minéraux et Biologiques, Unité Mixte de Recherche 7036 CNRS, Université Henri Poincaré Nancy I, BP 239, 54506 Vandoeuvre-lès-Nancy, France.
Morales
R
R
Contreras-Martel
C
C
Carpentier
P
P
Renault
F
F
Rochu
D
D
Chabriere
E
E
D043303:Aryldialkylphosphatase / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D001798:Blood Proteins / Q000737:chemistry* / Q000302:isolation & purification; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods*; D005583:Fourier Analysis; D006801:Humans; D008958:Models, Molecular; D011487:Protein Conformation
D001798:Blood Proteins; D043303:Aryldialkylphosphatase