THE PROTEOME OF SALMONELLA-ENTERICA SEROVAR TYPHIMURIUM - CURRENT PROGRESS ON ITS DETERMINATION AND SOME APPLICATIONS

Salmonella typhimurium (official designation Salmonella enterica serov ar Typhimurium) is an enteric pathogen and a principal cause of gastro enteritis in humans. A comprehensive description of the proteins of Sa lmonella and their patterns of expression under different environmenta l conditions would greatly increase our understanding of the virulence of this organism at the molecular level and provide insights into man y other aspects of Salmonella biology. While a variety of two-dimensio nal studies of Salmonella have been previously carried out to address specific questions, little systematic information is available at the protein level on the numbers of Salmonella polypeptides that have homo logues in other organisms, their abundance, and the frequency of postt ranslational modifications. To test the feasibility of determining the proteome of Salmonella, the identities of 53 randomly sequenced cell envelope proteins have been determined by N-terminal sequencing of spo ts from two-dimensional gels. In addition to confirming the existence of previously hypothetical proteins predicted from genomic sequencing projects, we found that approximately 20% of the proteins had no match es in sequence databases. The results suggest that proteome anlysis is an efficient way to identify novel proteins from prokaryotes and that the analysis provides a useful approach to the study of Salmonella vi rulence.