New model-fitting and model-completion programs for automated iterative nucleic acid refinement.

Autor: Yamashita K; Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan., Zhou Y, Tanaka I, Yao M
Jazyk: angličtina
Zdroj: Acta crystallographica. Section D, Biological crystallography [Acta Crystallogr D Biol Crystallogr] 2013 Jun; Vol. 69 (Pt 6), pp. 1171-9. Date of Electronic Publication: 2013 May 16.
DOI: 10.1107/S0907444913007191
Abstrakt: In the past decade many structures of nucleic acids have been determined, which have contributed to our understanding of their biological functions. However, crystals containing nucleic acids often diffract X-rays poorly. This makes electron-density interpretation difficult and requires a great deal of expertise in crystallography and knowledge of nucleic acid structure. Here, new programs called NAFIT and NABUILD for fitting and extending nucleic acid models are presented. These programs can be used as modules in the automated refinement system LAFIRE, as well as acting as independent programs. NAFIT performs sequential grouped fitting with empirical torsion-angle restraints and antibumping restraints including H atoms. NABUILD extends the model using a skeletonized map in a coarse-grained manner. It has been shown that NAFIT greatly improves electron-density fit and geometric quality and that iterative refinement with NABUILD significantly reduces the Rfree factor.
Databáze: MEDLINE