Abstract
During bacterial chemotaxis, attractants and repellents alter the methylation levels of the methyl-accepting chemotaxis proteins (MCP). These methylation levels represent balance between 2 enzymatic processes: methylation and demethylation. In vivo experiments previously showed that chemoeffectors influence the demethylation process; effects on the methylation system were not reported. In a cell-free extract of E. coli both methylation and demethylation of the MCP are affected by attractants and repellents. Attractants enhance methylation and inhibit demethylation. Repellents inhibit methylation and stimulate demethylation. The cell-free system provides an opportunity for further study of the mechanisms by which attractants and repellents influence the levels of methylation of the MCP.