Fosfomycin resistance: selection method for internal and extended deletions of the phosphoenolpyruvate:sugar phosphotransferase genes of Salmonella typhimurium

Abstract

Selection for resistance to the antibiotic fosfomycin (FOS; L-cis1,2-epoxypropylphosphonic acid, a structural analogue of phosphoenolpyruvate) was used to isolate mutants carrying internal and extended deletions of varying lengths within the ptsHI operon of Salmonella typhimurium. Strains carrying "tight" ptsI point mutations and all mutants in which some or all of the ptsI gene was deleted were FOS resistant. In contrast, strains carrying ptsH point mutations were sensitive to FOS. Resistance to FOS appeared to result indirectly from catabolite repression of an FOS transport system, probably the sn-glycerol-3phosphate transport system. Resistant ptsI mutants became sensitive to FOS when grown on i-glucose-6-phosphate, which induces an alternate transport system for FOS, or when grown in the presence of cyclic adenosine 3',5'monophosphate. A detailed fine-structure map of the pts gene region is presented. 785 on August 4, 2020 by guest

Phosphoenolpyruvate:carbohydrate phosphotransferase system of bacteria.

“…PTS-negative mutants have in general lowered cAMP levels, take up inducer at a lower rate, and grow more slowly (see below). Consequently, they are more resistant to antibiotics (e.g., nalidixic acid or amino glycosidic drugs) which act only on fast-growing cells and are fully resistant to drugs taken up via inducible transport systems, for instance fosfomycin (9,61,232). Any drug taken up via an inducible transport system and any phage or bacteriocin whose receptor requires cAMP for its synthesis can obviously be used in this type of selection, e.g., phage A in lamB+ strains carrying a functional lambda receptor (31, 43).…”

Altered Glucose Transport and Shikimate Pathway Product Yields in E.coli

“…coli JY1 was derived by P1 phage transduction of the ∆ptsHIcrr mutation of E. coli UE79 (21) into E. coli KL3 to inactivate PTS-mediated transport and phosphorylation of glucose. The lack of PTS-mediated glucose transport in E. coli JY1 was confirmed by its growth pattern on glucose, maltose containing fosfomycin, xylose, and xylose containing cAMP (16,25). Cultivation of E. coli JY1/pRC55B under fermentor-controlled conditions in M9 minimal medium with glucose as the carbon source and aromatic supplementation led to the emergence of a faster-growing variant that was designated E. coli JY1.2.…”

Phage display selection of peptides against enzyme I of the phosphoenolpyruvate–sugar phosphotransferase system (PTS)

“…The three effects, depletion of phosphoenolpyruvate, repression of catabolite controlled genes, and inhibition of carbohydrate transport should be enough to compromise cell growth and infectivity. This strategy differs from previously suggested schemes to exploit PTS transporters as vehicles for antibiotic uptake (Ammer et al, 1979;Parr and Saier, 1992) or to use analogues of phosphoenolpyruvate as antibacterials (Cordaro et al, 1976).…”