High-affinity l-arabinose transport operon : Gene product expression and mRNAs

• Published in: Journal of molecular biology Vol. 197; no. 1; pp. 27 - 35
• Main Authors: Horazdovsky, Bruce F., Hogg, Robert W.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 05.09.1987; Elsevier
• Subjects: Arabinose - genetics; Arabinose - metabolism; Bacteriology; Base Sequence; Biological and medical sciences; Biological Transport; Carrier Proteins; Cloning, Molecular; Escherichia coli; Escherichia coli - genetics; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genetics; Microbiology; Molecular Sequence Data; Operon; Plasmids; Protein Biosynthesis; RNA, Bacterial; RNA, Messenger; Operon; Escherichia coli; Gene expression; Characterization; Arabinose; Regulation(control); Messenger RNA; Membrane transport; Bacteria; Affinity; Molecular cloning; Escherichieae; Enterobacteriaceae
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/0022-2836(87)90606-1

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 M r protein that is the product of the promoter-proximal l-arabinose binding protein coding sequence, araF. A 52,000 M r 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 M r 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 S 1 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.