Pleiotropic mutations rendering Escherichia coli K-12 resistant to bacteriophage TP1.

tpo mutations, located at 74 min on the genetic map, rendered Escherichia coli K-12 resistant to TP1, a phage which can use either the OmpF protein or the LamB protein as its receptor. tpo mutants synthesized decreased amounts of OmpF and LamB proteins but increased amounts of the OmpC product, another outer membrane protein. The effect of the tpo mutations in lam B gene expression was transcriptional. It is one facet of the following effect on the maltose regulon: strong decreases in the syntheses of the LamB protein and the periplasmic MalE protein occurred when the regulon was uninduced; a lesser decrease occurred in the syntheses of the LamB protein the MalE protein, and the cytoplasmic MalQ protein (amylomaltase) when the regulon was induced. The tpo mutants were found to be phenotypically identical to the perA mutant recently described by Wanner et al. (J. Bacteriol. 140:229--239, 1979) and to some of the ompB mutants described by Verhoef et al. (Mol. Gen. Genet. 169:137--146, 1979). Mapping and complementation analysis suggested that these three types of mutations belong to the same cistron. Our results bring to at least four the number of clearly distinct phenotypes which can result from mutations at, or close to, ompB, a locus which appears increasingly complex.