Crystallography of ribosomes under microgravity Final report

Our long term goal is to elucidate the molecular structure of the ribosome by X-ray crystallography. In general, ribosomal particles display a marked tendency to form extremely thin crystals which tend to fracture, split or crack upon handling, causing a lose of precious synchrotron radiation time and sever difficulties in data collection and evaluation. As we consistently observed that significantly better crystallographic data could be collected from occasionally grown thicker crystals, we have invested a lot of effort in increasing the thickness of the crystals. Our aim was to grow crystals of more favorable morphologies. We assumed that tendency of the ribosomal particles to crystallize as thin plates is influenced by the contact of their nuclei with the flat surfaces of the growth chambers. Under microgravity conditions the situation should be different since the crystals are supposed to float freely, hence their contact with flat surfaces should be eliminated or reduced, facilitating the growth of thicker crystals. This aim fits well with the spirit and design of missions D2, IML-2 and UNSL-2, in which special facilities are allocated for the crystallization of biological macromolecules. We believe that we have introduced new dimensions not only to our studies on the structure and the function of ribosomes, but also to the experiments aimed at crystallization under microgravity conditions, due to the size and complexity of the ribosome, and due to the expected contribution of our studies to the general basic knowledge and understanding of crystallization of complex biological objects from one hand, and biological processes. We have participated in 10 missions of ESA and NASA. Despite the fact that in neither of these missions crystals suitable for data collection were grown, the preliminary results of these experiments proved to be rather helpful and shed light on several aspects of crystal growth alongside with illuminating strategies for further studies. Thus, the more growth of crystals showing indeed better morphology, in most of the crystallization chambers, indicates that given a larger statistical base, suitable crystals may grow. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(51,27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA) GmbH, Bonn (Germany)DEGerman