Permeabilization of cells for studies on the biochemistry of bacterial chemotaxis

The cell membranes of Salmonella typhimurium and Escherichia coli have been made permeable in order to introduce S-adenosylmethionine into the cell for study of the course of methylation. A series of protein bands in the Mr 60,000 region were methylated, the specific bands and the extent of methylation depending on the attractant used. The change in levels of methylation was essentially the same as the in vivo responses, indicating that the permeabilization procedure maintains the relative relationships of the cellular proteins. A shift in intensity of the methylated bands occurred over time, indicating that a sequential process is involved in the methylation of these proteins. The permeabilization technique appears to offer major advantages in tracing the biochemical processes of the behavioral system.