Characterization of a Unique Chromosomal Copper Resistance Gene Cluster from X anthomonas campestris pv. vesicatoria

Abstract

We characterized the copper resistance genes in strain XvP26 of Xanthomonas campestris pv. vesicatoria, which was originally isolated from a pepper plant in Taiwan. The copper resistance genes were localized to a 7,652-bp region which, based on pulsed-field gel electrophoresis and Southern hybridization, was determined to be located on the chromosome. These genes hybridized only weakly, as determined by Southern analysis, to other copper resistance genes in Xanthomonas and Pseudomonas strains. We identified five open reading frames (ORFs) whose products exhibited high levels of amino acid sequence identity to the products of previously reported copper genes. Mutations in ORF1, ORF3, and ORF4 removed copper resistance, whereas mutations in ORF5 resulted in an intermediate copper resistance phenotype and insertions in ORF2 had no effect on resistance conferred to a copper-sensitive recipient in transconjugant tests. Based on sequence analysis, ORF1 was determined to have high levels of identity with the CopR (66%) and PcoR (63%) genes in Pseudomonas syringae pv. tomato and Escherichia coli, respectively. ORF2 and ORF5 had high levels of identity with the PcoS gene in E. coli and the gene encoding a putative copper-containing oxidoreductase signal peptide protein in Sinorhizobium meliloti, respectively. ORF3 and ORF4 exhibited 23% identity to the gene encoding a cation efflux system membrane protein, CzcC, and 62% identity to the gene encoding a putative copper-containing oxidoreductase protein, respectively. The latter two ORFs were determined to be induced following exposure to low concentrations of copper, while addition of Co, Cd, or Zn resulted in no significant induction. PCR analysis of 51 pepper and 34 tomato copper-resistant X. campestris pv. vesicatoria strains collected from several regions in Taiwan between 1987 and 2000 and nine copper-resistant strains from the United States and South America showed that successful amplification of DNA was obtained only for strain XvP26. The organization of this set of copper resistance genes appears to be uncommon, and the set appears to occur rarely in X. campestris pv. vesicatoria.

The Copper-Inducible cin Operon Encodes an Unusual Methionine-Rich Azurin-Like Protein and a Pre-Q 0 Reductase in Pseudomonas putida KT2440

“…vesicatoria, cinA is associated with the multicopper oxidase, a TolC-like outer membrane protein, and a twocomponent heavy metal sensor kinase and response regulator. Basim et al (1) reported that for X. campestris pv. vesicatoria, disruption of cinA (ORF5) resulted in a partial loss of copper resistance, while disruption of the sensor kinase gene (ORF1), a multicopper oxidase gene (ORF4), or the TolC family outer membrane factor gene (ORF3) had a much greater effect.…”

Transcriptome of Geobacter uraniireducens growing in uranium-contaminated subsurface sediments

“…For example, a number of genes encoding proteins have been shown to be involved in bacterial resistance to such heavy metals as cobalt, zinc, cadmium, arsenic, copper, molybdenum and silver (Nies, 1995(Nies, , 1999Grunden and Shanmugam, 1997;Rensing et al, 1997Rensing et al, , 1999Brown et al, 2002;Parro and Moreno-Paz, 2003;Zahalak et al, 2004;Basim et al, 2005;Bencheikh-Latmani et al, 2005;Braz and Marques, 2005;Hu et al, 2005;Methe et al, 2005;Permina et al, 2006) and had higher transcript levels in sediment-grown cells (Table 7).…”

Molecular Characterization of Copper Resistance Genes from Xanthomonas citri subsp. citri and Xanthomonas alfalfae subsp. citrumelonis

“…Plasmid-borne genes for copper resistance in X. vesicatoria have similarities to the cop operon from P. syringae (43). Nevertheless, on the chromosome, the organization of the copper resistance genes appears to be uncommon, and occurrence of this type of resistance is rare in X. vesicatoria (3). The copper resistance genes described by Lee et al (22) in X. arboricola pv.…”

“…Although most copper resistance genes characterized from plant-pathogenic bacteria have been shown to be plasmid borne (4,6,12,26,37,43), chromosomal copper resistance genes have also been identified (3,22,23).…”

“…Copper resistance genes have also been cloned from Xanthomonas vesicatoria (3,12), Xanthomonas arboricola pv. juglandis (22), and Xanthomonas axonopodis pv.…”