title: Deoxycytidine deaminase-deficient Escherichia coli strains display acute sensitivity to cytidine, adenosine, and guanosine and increased sensitivity to a range of antibiotics, including vancomycin.
abstract: We show here that deoxycytidine deaminase (DCD)-deficient mutants of Escherichia coli are hypersensitive to killing by exogenous cytidine, adenosine, or guanosine, whereas wild-type cells are not. This hypersensitivity is reversed by exogenous thymidine. The mechanism likely involves the allosteric regulation of ribonucleotide reductase and severe limitations of the dTTP pools, resulting in thymineless death, the phenomenon of cell death due to thymidine starvation. We also report here that DCD-deficient mutants of E. coli are more sensitive to a series of different antibiotics, including vancomycin, and we show synergistic killing with the combination of vancomycin and cytidine. One possibility is that a very low, subinhibitory concentration of vancomycin enters Gram-negative cells and that this concentration is potentiated by chromosomal lesions resulting from the thymineless state. A second possibility is that the metabolic imbalance resulting from DCD deficiency affects the assembly of the outer membrane, which normally presents a barrier to drugs such as vancomycin. We consider these findings with regard to ideas of rendering Gram-negative bacteria sensitive to drugs such as vancomycin.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics and Molecular Biology Institute, University of California, and David Geffen School of Medicine, Los Angeles, California, USA.
authors.forename: Tina Manzhu
authors.initials: TM
authors.lastname: Kang
authors.forename: Jessica
authors.initials: J
authors.lastname: Yuan
authors.forename: Alice
authors.initials: A
authors.lastname: Zhou
authors.forename: Casey
authors.initials: C
authors.lastname: Beppler
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Miller
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003562:Cytidine / Q000494:pharmacology; D003564:Cytidine Deaminase; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006151:Guanosine / Q000494:pharmacology; D009700:Nucleoside Deaminases / Q000235:genetics / Q000378:metabolism*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D006151:Guanosine; D003562:Cytidine; D014640:Vancomycin; D009700:Nucleoside Deaminases; D003564:Cytidine Deaminase; C011530:deoxycytidine deaminase; D000241:Adenosine