New major outer membrane proteins found in an Escherichia coli tolF mutant resistant to bacteriophage TuIb

Abstract

Cell envelopes prepared from an Escherichia coli tolF strain selected as resistant to phage TuIb contained a new major outer membrane protein related to outer membrane proteins la and Ib. The strain that produces this protein is a tolF par double mutant but contains an additional mutation leading to the production of the new major outer membrane protein. Antibiotic sensitivity lost as a result of the tolF mutation is regained in strains that contain the new major outer membrane protein. This indicates that this protein functions to restore the selective permeability of the outer membrane to low-molecular-weight hydrophilic molecules.

Identification of three genes controlling production of new outer membrane pore proteins in Escherichia coli K-12

“…From this experiment it was concluded that there was no crossreactivity between the new membrane proteins and antiserum against protein la + lb. The reason for the discrepancy between our results and those of Foulds and Chai (9) is not known at present. DISCUSSION The results presented here indicate that at least three distinct genetic loci control some aspect of the production by E. coli K-12 of new major outer membrane proteins which are not normally expressed in wild-type strains.…”

“…However, only CS483 (NmpC+) was measurably more sensitive to colicin A. The Nmp+ strains remained fully resistant to colicins K, L, S4, and X, and remained sensitive to colicins B, D, G, H, Ia, Ib, M, Si, and V. We also examined strain JF720, a derivative of the Nmp+ strain described by Foulds and Chai (9), and found this strain to be almost fully sensitive to colicins E2 and E3, and therefore similar to our NmpA+ and NmpB+ mutants.…”

“…Strains carrying mutations in the par (meo) locus lack protein lb (2,29), and strains carrying mutations in the tolF-(also termed cmlB or cry) locus lack protein la (4,8). Strains with mutations in the ompB locus fail to produce either protein la or lb, as do strains carrying mutations in both par and tolF (9,12).…”

Two new peptidoglycan-associated proteins in the outer membrane of Escherichia coli K-12

“…Some other peptidoglyean-assoeiated proteins have been reported. One was found in cells lysogenized by phage PA2 [ 11 ] and the others were found in mutants having defects in 0-8 and/or 0-9 synthesis [12][13][14][15]. Judging from the migration position in a polyacrylamide gel, it is clear that neither O-13 nor O-14 is identical with any one of these peptidoglyean associated proteins.…”

Chromosomal location of a gene (nmpA) involved in expression of a major outer membrane protein in Escherichia coli

“…We have recently described one such revertant, strain JF694 (14). Strain JF694 is a tolF par strain that carries a third mutation which results in the appearance of a new major outer membrane protein we have called protein E (14). Other laboratories have reported strains that produce a similar new major outer membrane protein.…”