Outer membrane of Escherichia coli K-12: differentiation of proteins 3A and 3B on acrylamide gels and further characterization of con (tolG) mutants.

Two classes of mutants, con and tolG, that appeared to be very similar in a number of respects have been shown to be identical and cotransducible with pyrD. By diethylaminoethyl-cellulose chromatography of the outer membranes, we have shown that the mutants are missing only protein 3A and retain protein 3B. Using con mutants, we were thus able to identify protein 3B on the pH 7.2 gel system of Maizel where it runs separately from protein 3A if unheated samples are used. tolG mutants were shown to be identical to con mutants in being conjugation defective with most F-like plasmid donors but not with I-like plasmid donors, and in their resistance pattern to bacteriophages and colicins. During the course of this study, it was observed that the bacteriocin produced by Serratia marcescenc JF246 was identical in its activity spectrum to colicin L-398 and is now considered to be a colicin of type L.