Phage inhibition, colicin resistance, and tellurite resistance are encoded by a single cluster of genes on the IncHI2 plasmid R478.
AUTOR(ES)
Whelan, K F
RESUMO
A region of the IncHI2 plasmid R478, encoding the phenotypes of tellurite resistance (Ter), phage inhibition (Phi), and colicin resistance (PacB), was cloned and sequenced. Analysis indicated seven open reading frames (ORFs), whose genes were designated terZ, -A, -B, -C, -D, -E, and -F. Five of these predicted ORFs (A to E) had extensive amino acid homology with the previously reported ORFs of the IncHI2 Ter operon from plasmid pMER610. There were domains of highly conserved amino acid residues within the group TerA, -D, -E, and -F and within TerD, -E, and -Z, but no consensus could be found among all five putative polypeptides. There were also regions of good identity and similarity between individual pairs of ORFs which was not reflected in the multiple alignments. The three phenotypes were expressed in Escherichia coli DH5 alpha by an 8.4-kb EcoRI insert subcloned from a cosmid of R478. The latter insert was clonable only as a double insertion with a 4.5-kb fragment, and forced deletion of the smaller fragment was lethal to cells. This lethality was not dependent on the cloned orientation of either fragment, suggesting that there is a trans-acting element in the 4.5-kb fragment. Tn1000 mutagenesis of one of the double-insert clones, pDT2575, showed that the phenotypes, including multiple colicin resistance, were genetically linked. Transpositions into terD, terC, and terZ reduced or abolished all phenotypes, while inserts into terE and terF had no effect on the phenotypes. Insertions in terA reduced phage inhibition levels only. The presence of the terZ and terF ORFs in pMER610 was confirmed, and derivatives of this plasmid mediated Phi, PacB, and Ter.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=177279Documentos Relacionados
- Characterization of a region of the IncHI2 plasmid R478 which protects Escherichia coli from toxic effects specified by components of the tellurite, phage, and colicin resistance cluster.
- Restriction endonuclease mapping of the HI2 incompatibility group plasmid R478.
- Functional and Mutational Analysis of Conjugative Transfer Region 2 (Tra2) from the IncHI1 Plasmid R27
- The complete DNA sequence and analysis of R27, a large IncHI plasmid from Salmonella typhi that is temperature sensitive for transfer
- Functional and Mutational Analysis of Conjugative Transfer Region 1 (Tra1) from the IncHI1 Plasmid R27