Methylation of the cellular lipid of methionine-requiring Agrobacterium tumefaciens.

Mutants of Agrobacterium tumefaciens requiring methionine for growth on a solid basal medium were induced by the use of N-methyl-N'-nitro-N-nitrosoguanidine. In addition to the difference of mutant strains, the extent of methionine dependency differed in a liquid basal medium and in the presence of aspartate or fumarate. When ((14)C-methyl)-methionine was added to strain WM-11 growing in a prescribed basal medium, incorporation of (14)C into the cellular "residue" fraction and polar "N-methylated" lipid fraction depended strictly on cellular growth and on external methionine concentration. However, a net synthesis of the "cyclopropane" fatty acid fraction occurred even during the maximal stationary phase if excess methionine was present.