Analysis of Salmonella invasion protein-peptidoglycan interactions

Abstract

This chapter describes methods to analyze specific association of membrane proteins to the peptidoglycan layer. Emphasizes on the analysis of the Salmonella invasion type III secretion system (TTSS), the methods may be extrapolated to determinate protein-peptidoglycan interactions in other systems, including the flagellar apparatus and virulence-related TTSS of other bacterial pathogens. Macromolecular peptidoglycan from Salmonella typhimurium can be purified based on the method of Glauner. An experimental variable is the growth conditions at which bacteria are collected. If a major objective is to analyze interaction of Salmonella invasion proteins with the peptidoglycan, bacteria should be grown up to an invasion-competent phase. Additional areas of interest are the analysis of protein-peptidoglycan interactions in bacterial mutants harboring partial or fully assembled needle complexes as well as the identification of the protein domain(s) mediating their association to the peptidoglycan.