Initial interaction of the P22 phage with the Salmonella typhimurium surface

OBJECTIVES: The goals of these studies were to characterize the interaction of the P22 phage particle with the Salmonella cell surface and to determine the phage elements involved in this interaction by mutational analysis. BACKGROUND: The phage P22 has been characterized extensively. The gene and protein for the phage P22 tailspike, which is the phage adsorption organelle, have been intensively studied. The kinetics of the interaction of the tailspike protein with the cell surface has been studied in detail, surprisingly no mutational analysis has ever been reported that has defined these components and their interaction between themselves and the cell surface. The main and perhaps only component needed for this cell surface interaction is the tailspike protein. METHODS: Adsorption to the cell surface has been measured in the wild type phage and in mutant derivatives, isolated in this study. Phage mutants have been isolated after hydroxylamine mutagenesis. RESULTS: The adsorption of P22 to the cell surface is a temperature-independent event. Forty putative phage adsorption mutants have been isolated. A sample of them have been further analyzed. These divide the adsorption process into at least two stages. One stage contains mutants that absorb with essential wild type phage kinetics to the cell surface while the other stage with delayed adsorption kinetics. CONCLUSIONS: The interaction of the phage P22 with the Salmonella cell surface has been shown to be a complicated one which is temperature-independent and multi-stage. Mutants isolated in this study may help dissect this process even further

A tail of protein folding.

This review describes the use of a simple genetic system that has provided important insight into the process of folding and, of its flipside, that of protein aggregation. These studies make use of the tail protein of the bacterial virus P22 which infects Salmonella typhimurium. This folding system serves as a model for a number protein structural elements and may also provide important insights into disease-related protein folding defects at a time when an increasing number of diseases are being shown to be due to protein folding alterations.

Suppressor mutations derived from the most severe protein folding mutation known.

This brief report describes the isolation and initial characterization of revertants to the most severe temperature sensitive folding mutant known. The revertants or suppressors may describe amino acid interactions that occur during the folding of the P22 tailspike polypeptide chain. Results indicate that several different types of suppressors may have been obtained.