title: Identification of a second two-component signal transduction system that controls fosfomycin tolerance and glycerol-3-phosphate uptake.
abstract: Particular interest in fosfomycin has resurfaced because it is a highly beneficial antibiotic for the treatment of refractory infectious diseases caused by pathogens that are resistant to other commonly used antibiotics. The biological cost to cells of resistance to fosfomycin because of chromosomal mutation is high. We previously found that a bacterial two-component system, CpxAR, induces fosfomycin tolerance in enterohemorrhagic Escherichia coli (EHEC) O157:H7. This mechanism does not rely on irreversible genetic modification and allows EHEC to relieve the fitness burden that results from fosfomycin resistance in the absence of fosfomycin. Here we show that another two-component system, TorSRT, which was originally characterized as a regulatory system for anaerobic respiration utilizing trimethylamine-N-oxide (TMAO), also induces fosfomycin tolerance. Activation of the Tor regulatory pathway by overexpression of torR, which encodes the response regulator, or addition of TMAO increased fosfomycin tolerance in EHEC. We also show that phosphorylated TorR directly represses the expression of glpT, a gene that encodes a symporter of fosfomycin and glycerol-3-phosphate, and activation of the TorR protein results in the reduced uptake of fosfomycin by cells. However, cells in which the Tor pathway was activated had an impaired growth phenotype when cultured with glycerol-3-phosphate as a carbon substrate. These observations suggest that the TorSRT pathway is the second two-component system to reversibly control fosfomycin tolerance and glycerol-3-phosphate uptake in EHEC, and this may be beneficial for bacteria by alleviating the biological cost. We expect that this mechanism could be a potential target to enhance the utility of fosfomycin as chemotherapy against multidrug-resistant pathogens.
authors.affiliation: Advanced Scientific Research Leaders Development Unit, Gunma University, Graduate School of Medicine, Gunma, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Kurabayashi
authors.affiliation: Laboratory of Bacterial Drug Resistance, Gunma University, Graduate School of Medicine, Gunma, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hirakawa
authors.affiliation: Laboratory of Bacterial Drug Resistance, Gunma University, Graduate School of Medicine, Gunma, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Tanimoto
authors.affiliation: Department of Bacteriology, Gunma University, Graduate School of Medicine, Gunma, Japan Laboratory of Bacterial Drug Resistance, Gunma University, Graduate School of Medicine, Gunma, Japan.
authors.forename: Haruyoshi
authors.initials: H
authors.lastname: Tomita
authors.affiliation: Advanced Scientific Research Leaders Development Unit, Gunma University, Graduate School of Medicine, Gunma, Japan hirakawa@gunma-u.ac.jp.
authors.forename: Hidetada
authors.initials: H
authors.lastname: Hirakawa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001692:Biological Transport; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005578:Fosfomycin / Q000494:pharmacology*; D005994:Glycerophosphates / Q000378:metabolism*; D033903:Periplasmic Proteins / Q000235:genetics / Q000378:metabolism*; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D005994:Glycerophosphates; D033903:Periplasmic Proteins; C089364:TorR protein, E coli; C098062:TorT protein, E coli; D014157:Transcription Factors; D005578:Fosfomycin; C029620:alpha-glycerophosphoric acid; D010770:Phosphotransferases; C103806:TorS protein, E coli