The plasmid-encoded chloramphenicol-resistance protein of Rhodococcus fascians is homologous to the transmembrane tetracycline efflux proteins.
The nucleotide sequence of the chloramphenicol-resistance gene (cmr) of Rhodococcus fascians NCPPB 1675 (located on the conjugative plasmid pRF2) allowed the identification of two possible open reading frames (ORFs), of which ORF1 was consistent with the mutational analysis. Biochemical analysis of cmr revealed that it does not encode an antibiotic-modifying enzyme. The amino acid sequence of ORF1 predicted a hydrophobic protein, with 12 putative membrane-spanning domains, homologous to proteins involved in the efflux of tetracycline across the plasma membrane. Expression of the cmr gene was induced by addition of chloramphenicol to the growth media. The promoter of this gene was restricted to 50 bp upstream from a 200 bp 5'-untranslated mRNA region, the latter containing two inverted repeats. At the amino acid level, the cmr gene is 52% identical to a previously identified chloramphenicol-resistance determinant in Streptomyces lividans, indicating a wider dispersion of this type of cmr gene among the actinomycetes.
Desomer
J
J
Laboratorium voor Genetica, Universiteit Gent, Belgium.
Vereecke
D
D
Crespi
M
M
Van Montagu
M
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002701:Chloramphenicol / Q000494:pharmacology; D002702:Chloramphenicol Resistance / Q000235:genetics; D003062:Codon; D004269:DNA, Bacterial; D015870:Gene Expression / Q000187:drug effects; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011815:R Factors; D012097:Repressor Proteins / Q000235:genetics; D015183:Restriction Mapping; D012240:Rhodococcus / Q000187:drug effects / Q000235:genetics*; D017385:Sequence Homology
D001426:Bacterial Proteins; D003062:Codon; D004269:DNA, Bacterial; D008565:Membrane Proteins; D012097:Repressor Proteins; C034811:tetracycline resistance-encoding transposon repressor protein; C077001:CMR protein, Rhodococcus fascians; D002701:Chloramphenicol