Identification of a gene encoding a bacteriophage-related integrase in a vap region of the Dichelobacter nodosus genome.
ABSTRACT Dichelobacter nodosus is the principal causative agent of ovine footrot. Nucleotide (nt) sequences from the D. nodosus genome have been isolated and a series of overlapping lambda clones defining vap (virulence-associated protein) regions 1, 2 and 3 have been reported [Katz et al., J. Bacteriol. 176 (1994) 2663-2669]. In the present study, the limits of the virulence-associated (va) DNA around vap regions 1 and 3 were determined by dot-blot hybridization experiments using plasmid subclones to probe genomic DNA from the D. nodosus virulent strain A198 and the benign strain C305. This va region was found to be approx. 11.9 kb in length, and to be interrupted by a short DNA segment which is also found in the benign D. nodosus strain. Sequence analysis of the entire region revealed an ORF, intA, which is very similar to the integrases of bacteriophages phi R73, P4 and Sf6. Bacteriophages phi R73 and P4 integrate into the 3' ends of tRNA genes, with the integrase genes adjacent to the tRNA genes. A similar arrangement was found in the D. nodosus va region. A 19-bp nt sequence was found to be repeated at the ends of the va region, and may represent the bacteriphage attachment site. These findings suggest that D. nodosus may have acquired these DNA sequences by the integration of a bacteriophage, or an integrative plasmid that contains a bacteriophage-related integrase gene. The high similarity of the D. nodosus integrase to integrases from coliphages suggests that these va sequences may be transferred between distantly related bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)
- SourceAvailable from: sciencedirect.comFebs Letters - FEBS LETT. 01/1973; 29(3):231-234.
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ABSTRACT: We have cloned from Pseudomonas putida a gene homologous to Escherichia coli dnaA, and determined the sequence of the gene and its neighboring region. The dnaA gene and at least three other genes, dnaN, recF and gyrB, were found to be highly homologous to the genes in the dnaA regions of the E. coli and Bacillus subtilis chromosomes. A non-translatable region of some 600 bp immediately upstream of the dnaA gene is also conserved in the three bacteria and contains 3, 12, and 14 DnaA-boxes (TTATCCACA and closely related sequences) in E. coli, P. putida and B. subtilis, respectively. The present results confirm our hypothesis that the dnaA region is the replication origin region of the ancestral bacterium and that the essential feature of the dnaA and DnaA-box combination is conserved in most eubacteria and plays a central role in initiation of chromosomal replication.MGG - Molecular and General Genetics 01/1989; 215(3):381-387.
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ABSTRACT: Dichelobacter nodosus (formerly Bacteroides nodosus) is a Gram-negative strict anaerobe and is the primary pathogen involved in ovine footrot. A comparative hybridization strategy was used to isolate recombinant clones which hybridized to DNA from a virulent strain of D. nodosus but not with a benign isolate. Three virulence-associated gene regions were identified and one of these regions was shown to be present in multiple copies in the D. nodosus genome. Hybridization studies on 101 clinical isolates of D. nodosus showed that these strains could be divided into three hybridization categories which could be correlated with the virulence of the isolates. The recombinant clones have considerable potential for the development of a gene-probe-based method for the differential diagnosis of ovine footrot.Journal of general microbiology 10/1991; 137(9):2117-24.