Open AccessIsolation and characterization of kikA, a region on IncN group plasmids that determines killing of Klebsiella oxytoca
Author(s) -
Paul N. Hengen,
D. Denicourt,
V. N. Iyer
Publication year - 1992
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.174.9.3070-3077.1992
Subject(s) - biology , klebsiella oxytoca , plasmid , orfs , enterobacter aerogenes , open reading frame , escherichia coli , gene , nucleic acid sequence , genetics , dna , microbiology and biotechnology , enterobacteriaceae , peptide sequence
Transfer of the IncN group plasmid pCU1 from Escherichia coli to Klebsiella oxytoca by conjugation kills a large proportion (90 to 95%) of the recipients of plasmid DNA, whereas transfer to E. coli or even to the closely related Enterobacter aerogenes does not. Two regions, kikA and kikB, have been identified on pCU1 that contribute to the Kik (killing in klebsiellas) phenotype. We have localized the kikA region to 500 bp by deletion analysis and show by DNA-DNA hybridization that kikA is highly conserved among the plasmids of incompatibility group N. The expression in K. oxytoca of kikA under the control of the strong inducible E. coli tac promoter results in loss of cell viability. The nucleotide sequence showed two overlapping open reading frames (ORFs) within the kikA region. The first ORF codes for a putative polypeptide of 104 amino acids (ORF104). The second ORF codes for a 70-amino-acid polypeptide (ORF70). The properties of the putative protein encoded by ORF104 and gene fusions of kikA to alkaline phosphatase by using TnphoA suggest that killing may involve an association with the bacterial membrane; however, we could not rule out the possibility that ORF70 plays a role in the Kik phenotype.