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- Title
Molecular genetics and transport analysis of the copper-resistance determinant (pco) from Escherichia coli plasmid pRJ1004.
- Authors
Brown, Nigel L.; Barrett, Siobhan R.; Camakaris, James; Lee, Barry T. O.; Rouch, Duncan A.
- Abstract
The copper-resistance determinant (<em>pco</em>) of <em>Escherichia coli</em> plasmid pRJ1004 was cloned and sequenced. Tn<em>1000</em> transposon mutagenesis identified four complementation groups, mutations in any of which eliminated copper resistance. DNA sequence analysis showed that the four complementation groups contained six open reading frames, designated <em>pco-ABCDRS</em>. The protein product sequences derived from the nucleotide sequence show close homology between this copper-resistance system and the <em>cop</em> system of a plasmid pPT23D of <em>Pseudomonas syringae</em> pv. tomato. The PcoR and PcoS protein sequences show homology to the family of two-component sensor/responder phosphokinase regulatory systems. A seventh reading frame (<em>pcoE</em>) was identified from DNA sequence data, and lies downstream of a copper-regulated promoter. Transport assays with 64Cu(II) showed that the resistant cells containing the plasmid had reduced copper accumulation during the log phase of growth, while increased accumulation had previously been observed during stationary phase. Chromosomal mutants defective in cellular copper management were obtained and characterized. In two of these mutants <em>pco</em> resistance was rendered totally inactive, whilst in another two mutants <em>pco</em> complemented the defective genes. These data indicate that plasmid-borne copper resistance in <em>E. coli</em> is linked with chromosomal systems for copper management.
- Subjects
ESCHERICHIA coli; PLASMIDS; MOLECULAR genetics; CYTOPLASMIC inheritance; ESCHERICHIA
- Publication
Molecular Microbiology, 1995, Vol 17, Issue 6, p1153
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.1995.mmi_17061153.x