title: Unusual transcriptional and translational features of the aminoglycoside phosphotransferase gene (aph) from Streptomyces fradiae.
abstract: The aminoglycoside phosphotransferase gene (aph) from the neomycin producer Streptomyces fradiae encodes an enzyme (APH) that phosphorylates, and thereby inactivates, the antibiotic neomycin. Two promoters were identified upstream of and oriented toward the aph coding sequence. One promoter (aphp1) initiated transcription at the A of the ATG translational initiation codon, or one to two bases upstream. Mutations made in this promoter region identified functionally important nucleotides and verified that the aphp1 transcript was translated to yield the APH protein, despite the lack of a conventional ribosome binding site. A second aph promoter, aphp2, initiated transcription 315 bp upstream of the translational initiation codon but gave transcripts that appeared to terminate before reaching the coding sequence. Multiple transcriptional initiation sites (pA1-pA5) were identified also in the aph regulatory region oriented in the opposite direction to aph transcription. Promoters for the pA2 and pA4 transcripts overlap with aphp1 such that down-promoter mutations in aphp1 also reduce transcription from the overlapping pA promoters.
authors.affiliation: John Innes Institute, Norwich, UK.
authors.forename: G R
authors.initials: GR
authors.lastname: Janssen
authors.forename: J M
authors.initials: JM
authors.lastname: Ward
authors.forename: M J
authors.initials: MJ
authors.lastname: Bibb
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002874:Chromosome Mapping; D003062:Codon; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004720:Endonucleases; D005090:Exodeoxyribonucleases; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D019868:Kanamycin Kinase; D008969:Molecular Sequence Data; D009154:Mutation; D010770:Phosphotransferases / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012270:Ribosomes / Q000378:metabolism; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics*; D014158:Transcription, Genetic; D014169:Transformation, Bacterial
chemical_list: D003062:Codon; D004269:DNA, Bacterial; D010770:Phosphotransferases; D019868:Kanamycin Kinase; D004720:Endonucleases; D005090:Exodeoxyribonucleases; C026870:exodeoxyribonuclease VII; D015719:Single-Strand Specific DNA and RNA Endonucleases