Molecular genetics and transport analysis of the copper-resistance determinant (pco) from Escherichia coli plasmid pRJ1004

• Published in: Molecular microbiology Vol. 17; no. 6; p. 1153
• Main Authors: Brown, N L, Barrett, S R, Camakaris, J, Lee, B T, Rouch, D A
• Format: Journal Article
• Language: English
• Published: England 01.09.1995
• Subjects: Amino Acid Sequence; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - physiology; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Biological Transport, Active; Carrier Proteins - genetics; Carrier Proteins - physiology; Cation Transport Proteins; Chromosomes, Bacterial; Cloning, Molecular; Consensus Sequence; Copper - metabolism; Copper - pharmacology; DNA Transposable Elements; DNA, Bacterial - genetics; DNA-Binding Proteins - genetics; DNA-Binding Proteins - physiology; Drug Resistance, Microbial - genetics; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genes, Regulator; Genetic Complementation Test; Models, Biological; Molecular Sequence Data; Mutagenesis, Insertional; Operon; Pseudomonas - genetics; R Factors - genetics; Recombinant Fusion Proteins - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Trans-Activators - genetics; Trans-Activators - physiology; Transferases; Xanthomonas campestris - genetics
• ISSN: 0950-382X
• DOI: 10.1111/j.1365-2958.1995.mmi_17061153.x

The copper-resistance determinant (pco) of Escherichia coli plasmid pRJ1004 was cloned and sequenced. Tn1000 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 pco-ABCDRS. The protein product sequences derived from the nucleotide sequence show close homology between this copper-resistance system and the cop system of a plasmid pPT23D of Pseudomonas syringae 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 (pcoE) 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 pco resistance was rendered totally inactive, whilst in another two mutants pco complemented the defective genes. These data indicate that plasmid-borne copper resistance in E. coli is linked with chromosomal systems for copper management.