Publications

• Susceptibility of Escherichia coli to the toxic L-proline analogue L-selenaproline is dependent on two L-cystine transport systems.

  Deutch C.E., Spahija I., Wagner C.E.

  <h4>Aims</h4>L-Selenaproline (L-selenazolidine-4-carboxylic acid) is a toxic analogue of L-proline that inhibits the growth of the urinary tract pathogen Escherichia coli in both laboratory culture media and normal human urine. The aim of this study was to identify the transport systems involved i ... >> More

  <h4>Aims</h4>L-Selenaproline (L-selenazolidine-4-carboxylic acid) is a toxic analogue of L-proline that inhibits the growth of the urinary tract pathogen Escherichia coli in both laboratory culture media and normal human urine. The aim of this study was to identify the transport systems involved in its uptake.<h4>Methods and results</h4>Deletion mutants from the Keio collection were tested for their susceptibility to L-selenaproline (SCA) and L-selenocystine (SeCys) on minimal salts agar medium. All single-gene mutants were sensitive to both compounds, but double mutants with deletions in fliY and ydjN or in yecS and ydjN were resistant to SCA and SeCys. The YdjN transporter active in strain JW1905 (ΔfliY::kan yecC(+) yecS(+) ydjN(+)) was inhibited by both SCA and SeCys, but the FliY YecS YecC ABC transporter system active in strain JW1718 (fliY(+) yecC(+) yecS(+) ΔydjN::kan) was best inhibited by these compounds in the presence of dithiothreitol.<h4>Conclusions</h4>L-selenaproline and L-selenocystine are accumulated by both the FliY YecC YecS and the YdjN L-cystine transporter systems in E. coli.<h4>Significance and impact of the study</h4>Because susceptibility to selenium-containing analogues of L-proline and L-cystine is dependent on multiple transport systems, these compounds may be effective in the treatment of urinary tract infections. << Less

  J. Appl. Microbiol. 117:1487-1499(2014) [PubMed] [EuropePMC]

• Cysteine is exported from the Escherichia coli cytoplasm by CydDC, an ATP-binding cassette-type transporter required for cytochrome assembly.

  Pittman M.S., Corker H., Wu G., Binet M.B., Moir A.J., Poole R.K.

  Assembly of Escherichia coli cytochrome bd and periplasmic cytochromes requires the ATP-binding cassette transporter CydDC, whose substrate is unknown. Two-dimensional SDS-PAGE comparison of periplasm from wild-type and cydD mutant strains revealed that the latter was deficient in several periplas ... >> More

  Assembly of Escherichia coli cytochrome bd and periplasmic cytochromes requires the ATP-binding cassette transporter CydDC, whose substrate is unknown. Two-dimensional SDS-PAGE comparison of periplasm from wild-type and cydD mutant strains revealed that the latter was deficient in several periplasmic transport binding proteins, but no single major protein was missing in the cydD periplasm. Instead, CydDC exports from cytoplasm to periplasm the amino acid cysteine, demonstrated using everted membrane vesicles that transported radiolabeled cysteine inward in an ATP-dependent, uncoupler-independent manner. New pleiotropic cydD phenotypes are reported, including sensitivity to benzylpenicillin and dithiothreitol, and loss of motility, consistent with periplasmic defects in disulfide bond formation. Exogenous cysteine reversed these phenotypes and affected levels of periplasmic c-type cytochromes in cydD and wild-type strains but did not restore cytochrome d. Consistent with CydDC being a cysteine exporter, cydD mutant growth was hypersensitive to high cysteine concentrations and accumulated higher cytoplasmic cysteine levels, as did a mutant defective in orf299, encoding a transporter of the major facilitator superfamily. A cydD orf299 double mutant was extremely cysteine-sensitive and had higher cytoplasmic cysteine levels, whereas CydDC overexpression conferred resistance to high extracellular cysteine concentrations. We propose that CydDC exports cysteine, crucial for redox homeostasis in the periplasm. << Less

  J. Biol. Chem. 277:49841-49849(2002) [PubMed] [EuropePMC]

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