Biomaterial Database

Topological analysis of DctQ, the small integral membrane protein of the C4-dicarboxylate TRAP transporter of Rhodobacter capsulatus. 2001

N R Wyborn, and J Alderson, and S C Andrews, and D J Kelly

Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, S10 2TN, UK.

Tripartite ATP-independent periplasmic ('TRAP') transporters are a novel group of bacterial and archaeal secondary solute uptake systems which possess a periplasmic binding protein, but which are unrelated to ATP-binding cassette (ABC) systems. In addition to the binding protein, TRAP transporters contain two integral membrane proteins or domains, one of which is 40-50 kDa with 12 predicted transmembrane (TM) helices, thought to be the solute import protein, while the other is 20-30 kDa and of unknown function. Using a series of plasmid-encoded beta-lactamase fusions, we have determined the topology of DctQ, the smaller integral membrane protein from the high-affinity C4-dicarboxylate transporter of Rhodobacter capsulatus, which to date is the most extensively characterised TRAP transporter. DctQ was predicted by several topology prediction programmes to have four TM helices with the N- and C-termini located in the cytoplasm. The levels of ampicillin resistance conferred by the fusions when expressed in Escherichia coli were found to correlate with this predicted topology. The data have provided a topological model which can be used to test hypotheses concerning the function of the different regions of DctQ and which can be applied to other members of the DctQ family.

UI	MeSH Term	Description	Entries
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D011993	Recombinant Fusion Proteins	Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.	Fusion Proteins, Recombinant,Recombinant Chimeric Protein,Recombinant Fusion Protein,Recombinant Hybrid Protein,Chimeric Proteins, Recombinant,Hybrid Proteins, Recombinant,Recombinant Chimeric Proteins,Recombinant Hybrid Proteins,Chimeric Protein, Recombinant,Fusion Protein, Recombinant,Hybrid Protein, Recombinant,Protein, Recombinant Chimeric,Protein, Recombinant Fusion,Protein, Recombinant Hybrid,Proteins, Recombinant Chimeric,Proteins, Recombinant Fusion,Proteins, Recombinant Hybrid
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D003998	Dicarboxylic Acids	Acyclic acids that contain two carboxyl groups and have the formula HO2C-R-CO2H, where R may be an aromatic or aliphatic group.	Acids, Dicarboxylic
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001618	beta-Lactamases	Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.	beta-Lactamase,beta Lactamase,beta Lactamases
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill