- Regulation of methionine synthesis in Escherichia coli: effect of the MetR protein on the expression of the metE and metR genes. Maxon, M.E., Redfield, B., Cai, X.Y., Shoeman, R., Fujita, K., Fisher, W., Stauffer, G., Weissbach, H., Brot, N. Proc. Natl. Acad. Sci. U.S.A. (1989)