title: On the mechanism of resistance to channel-forming colicins (PacB) and tellurite, encoded by plasmid Mip233 (IncHI3).
abstract: Plasmids of the H incompatibility complex confer protection against all known channel-forming colicins (PacB character) and resistance to potassium tellurite (Te(r)) to Escherichia coli strains. A DNA clone (2.2 kbp) from plasmid Mip233 (IncHI3) expressing PacB-Te(r) phenotypes was studied. DNA sequence analysis revealed a high degree of homology with the enzyme O-acetylserine sulfhydrylase. Size of the PacB-Te(r) transcript was estimated as 1200 bases. A single polypeptide was found on SDS-polyacrylamide gel with a molecular mass estimated of 34 kDa. The effect of channel-forming colicins and tellurite was analyzed at physiological and transcriptional levels. Results suggest that the pacB gene product could be a reductase-like enzyme. It is also suggested that presence of the PacB character among H plasmid confers selective advantage on cells sharing an ecological niche.
authors.affiliation: Instituto de Biología Experimental, Facultad de Ciencias, Universidad Central de Venezuela, 1041A, Caracas, Venezuela. galonso@reacciun.ve
authors.forename: G
authors.initials: G
authors.lastname: Alonso
authors.forename: C
authors.initials: C
authors.lastname: Gomes
authors.forename: C
authors.initials: C
authors.lastname: González
authors.forename: V
authors.initials: V
authors.lastname: Rodríguez Lemoine
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D003087:Colicins / Q000378:metabolism / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000096:biosynthesis / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D013691:Tellurium / Q000378:metabolism / Q000494:pharmacology*; D014158:Transcription, Genetic
chemical_list: D003087:Colicins; D010455:Peptides; D012329:RNA, Bacterial; D012333:RNA, Messenger; D013691:Tellurium