FIG. 3.

Methylesterification of E. coli proteins in PIMT-overproducing and control strains. The methyl-accepting activity of E. coli extracts was determined after incubation of intact bacteria (lane 1, strain JC196(pTBGH+); lane 2, strain JC196(pTBGH+), overproducing PIMT; lane 3, strain JC196) at the end of exponential phase with ³H-labeled methionine for 30 min, ultrasonic lysis of bacteria, and autoradiography of polyacrylamide gels after electrophoresis at pH 2.4, as described in Materials and Methods. The arrow indicates the position of preS2-S′-β-galactosidase.