title: High-affinity L-arabinose transport operon. Gene product expression and mRNAs.
abstract: Various portions of the "high-affinity" L-arabinose transport operon were cloned into the plasmid expression vector pKK223-3 and the operon-encoded protein products were identified. The results indicate that three proteins are encoded by this operon. The first is a 33,000 Mr protein that is the product of the promoter-proximal L-arabinose binding protein coding sequence, araF. A 52,000 Mr protein is encoded by sequence 3' to araF and has been assigned to the araG locus. The sequence 3' to araG encodes a 31,000 Mr protein that has been assigned to the araH locus. Both the araG and araH gene products are localized in the membrane fraction of the cell, implying a role in the membrane-associated complex of the high-affinity L-arabinose transport system. Nuclease S1 protection studies indicate that two operon message populations are present in the cell, a full-length operon transcript and a seven- to tenfold more abundant binding protein-specific message. The relative abundance of these two message populations correlates with the differential expression of the binding protein and the membrane-associated proteins of the transport system.
mesh_terms: D001089:Arabinose / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D010957:Plasmids; D014176:Protein Biosynthesis; D012329:RNA, Bacterial; D012333:RNA, Messenger
chemical_list: C016242:AraF protein, E coli; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001089:Arabinose