Techniques for cloning cDNAs encoding interactive transcriptional regulatory proteins

Biochemical approaches for characterizing RNA-protein complexes in preparation for high resolution structure analysis

RNA-protein interactions control viral RNA replication, transcription, translation, and particle assembly. Progress toward understanding the functional significance of RNA-protein complexes in the viral life cycle is hindered by the lack of high resolution structural information. Challenges to acquiring structural data include RNA's inherent instability and conformational plasticity, coupled with the comparatively high cost of generating large quantities of RNA for biophysical experiments. The potential for successful structure determination is increased by conducting biochemical experiments that outline interacting domains and identify key residues. These approaches are aimed at defining and characterizing RNA and protein substrates that are suitable for high resolution structural analysis.

Biotechnological applications of phage and cell display

In recent years, the use of surface-display vectors for displaying polypeptides on the surface of bacteriophage and bacteria, combined with in vitro selection technologies, has transformed the way in which we generate and manipulate ligands, such as enzymes, antibodies and peptides. Phage display is based on expressing recombinant proteins or peptides fused to a phage coat protein. Bacterial display is based on expressing recombinant proteins fused to sorting signals that direct their incorporation on the cell surface. In both systems, the genetic information encoding for the displayed molecule is physically linked to its product via the displaying particle. Using these two complementary technologies, we are now able to design repertoires of ligands from scratch and use the power of affinity selection to select those ligands having the desired (biological) properties from a large excess of irrelevant ones. With phage display, tailor-made proteins (fused peptides, antibodies, enzymes, DNA-binding proteins) may be synthesized and selected to acquire the desired catalytic properties or affinity of binding and specificity for in vitro and in vivo diagnosis, for immunotherapy of human disease or for biocatalysis. Bacterial surface display has found a range of applications in the expression of various antigenic determinants, heterologous enzymes, single-chain antibodies, and combinatorial peptide libraries. This review explains the basis of phage and bacterial surface display and discusses the contributions made by these two leading technologies to biotechnological applications. This review focuses mainly on three areas where phage and cell display have had the greatest impact, namely, antibody engineering, enzyme technology and vaccine development.