Comparison of Escherichia coli and rabbit reticulocyte ribosome display systems

Ribosome display is a technology for library selection and simultaneous mol ecular evolution in vitro. We present here a comparison between an optimize d Escherichia coli system and different rabbit reticulocyte ribosome displa y systems, optimized in a number of parameters, as a coupled eukaryotic sys tem had been suggested to result in high enrichment factors [He and Taussig (1997) Nucleic Acids Res. 25, 5132-5134], With all systems, antibody scFv fragments, complexed to the ribosomes and the corresponding mRNA, were enri ched by binding to their cognate antigen and enrichment was always dependen t on the absence of a stop codon and the presence of cognate antigen. Howev er, the efficiency of the E, coli ribosome display system was 100-fold high er than an optimized uncoupled rabbit reticulocyte ribosome display system, with separate in vitro transcription and translation, which was in turn se veral-fold more efficient than the reported coupled system. Neither the E, coil nor the rabbit reticulocyte ribosome display system was dependent on t he orientation of the domains of an antibody scFv fragment or on the spacer sequence, In summary, we could not detect any intrinsic advantage of using a eukaryotic translation system for ribosome display. (C) 1999 Federation of European Biochemical Societies.