Crystallization and X-ray diffraction data of Thermus flavus 5S rRNA helices

5S rRNA is an essential component of the large ribosomal subunit in prokary otes and eukaryotes. Its unknown function in the ribosome will eventually b e revealed in part by structural studies. To promote crystallization and en hance resolution in X-ray diffraction the molecule was subdivided into five domains A-E. Several RNA oligonucleotides were chemically produced by soli d-phase phosphoramidite synthesis in order to construct the domains of the 5S rRNA. An improved RNA-MPD-screen was applied in crystallization which co vers a complete 2D matrix for the components used. Crystallization analysis resulted in preferred combinations of pH, polyamine, monovalent and divale nt cations for short RNA molecules. Six types of crystals corresponding to the domains B, C and E of Thermus flavus 5S rRNA could be obtained which we re suitable for X-ray diffraction. Four RNA helices consist of seven base p airs and two of eight base pairs. As special features, they contain two ade nines in a bulge position or G:U wobble base pairs assumed to be involved i n RNA-protein recognition. With an increase in crystal size an increase in resolution by X-ray analysis was observed. X-ray diffraction data were coll ected to 1.5 Angstrom resolution using synchrotron radiation and cryogenic cooling techniques. (C) 2001 Elsevier Science B.V. All rights reserved.