SPECIFIC DETECTION OF SALMONELLA-TYPHIMURIUM PROTEINS SYNTHESIZED INTRACELLULARLY

Studies of the proteins Salmonella typhimurium synthesizes under condi tions designed to more closely approximate the in vivo environment, i. e., in cell and tissue culture, are not easily interpreted because the y have involved chemical inhibition of host cell protein synthesis dur ing infection. The method,which,ve have developed allows specific labe ling of bacterial proteins without interfering with host cell metaboli c activities by using a labeled lysine precursor which mammalian cells cannot utilize. We have resolved the labeled proteins using two-dimen sional electrophoresis and autofluorography. We were able to detect 57 proteins synthesized by S. typhimurium during growth within a human i ntestinal epithelial cell line. Of the 57 proteins detected, 34 appear to be unique to the intracellular environment, i.e., they are not see n during growth of the bacteria in tissue culture medium alone. Curren t (and future) efforts are directed at organizing the 34 proteins into known stress response groups, determining the cellular locations of t he proteins (outer or inner membrane, etc.), and comparing the pattern of proteins synthesized within an intestinal epithelial cell to the p attern synthesized during growth within other tissues.