On the solution of the molecular-replacement problem at very low resolution: application to large complexes

Alexandr Urzhumtsev (1) , Alberto Podjarny (1)

1 IGBMC - Institut de Génétique et de Biologie Moléculaire et Cellulaire

The applicability of the molecular-replacement (MR) method, implemented through the AMoRe package [Navaza (1994). Acta Cryst. A50, 157-163], is studied at very low resolution (d > 20 A) and for very large molecular complexes. Due to the nature of the low-resolution data, specific problems appear. In particular, rotation-function peaks are very broad and translation functions based on Patterson overlap show large spurious peaks. To solve these problems, the translation function is replaced by a search using amplitude correlation and a systematic three-dimensional angular search is performed around each rotation-function peak. Furthermore, these functions are applied in different resolution ranges during the same search. The corresponding algorithms are applied to two cases: the tRNA(Asp)-synthetase complex (neutron diffraction data) and a ribosome model crystal (calculated data). This new implementation is shown to solve the problem for a variety of search models, ranging from a detailed atomic model to a rough envelope.

Domaines: Biochimie, Biologie Moléculaire

Alexandr Urzhumtsev, Alberto Podjarny. On the solution of the molecular-replacement problem at very low resolution: application to large complexes. Acta Crystallographica Section D: Biological Crystallography, 1995, 51 (Pt 6), pp.888-895. ⟨10.1107/S0907444995006743⟩. ⟨hal-04001492⟩