INSERTIONAL MUTAGENESIS IN THE TAILSPIKE PROTEIN OF BACTERIOPHAGE-P22

The tailspike protein (TSP) of bacteriophage P22 is a homotrimeric mul tifunctional protein responsible for recognition and hydrolysis of Sal monella typhimurium host receptors, Once properly folded, TSP shows an unusual stability to temperature and detergent denaturation, promptin g the analysis of TSP as a framework for the positioning of heterologo us protein segments. We have explored the flexibility of inner sites a nd both amino and carboxy termini to accommodate foreign peptides for phage display, In the examined inner sites, TSP is extremely sensitive to minor sequence modifications, the folding intermediates being rapi dly degraded. However, both the amino and carboxy termini are tolerant to peptide fusions, rendering stable and functional chimeric proteins . Surprisingly, the amino terminus, which connects the tail to the nec k structure, can accept large peptide fusions, and the foreign amino a cid stretches are solvent-exposed and highly antigenic on assembled, i nfectious virus particles. (C) 1998 Academic Press.