Escherichia coli possesses two homologous anaerobic C4-dicarboxylate membrane transporters (DcuA and DcuB) distinct from the aerobic dicarboxylate transport system (Dct).
The nucleotide sequences of two Escherichia coli genes, dcuA and dcuB (formerly designated genA and genF), have been shown to encode highly homologous products, M(r) 45,751 and 47,935 (434 and 446 amino acid residues) with 36% sequence identity (63% similarity). These proteins have a high proportion (approximately 61%) of hydrophobic residues and are probably members of a new group of integral inner membrane proteins. The locations of the dcu genes, one upstream of the aspartase gene (dcuA-aspA) and the other downstream of the anaerobic fumarase gene (fumB-dcuB), suggested that they may function in the anaerobic transport of C4-dicarboxylic acids. Growth tests and transport studies with mutants containing insertionally inactivated chromosomal dcuA and dcuB genes show that their products perform analogous and mutually complementary roles as anaerobic dicarboxylate carriers. The anaerobic dicarboxylate transport systems (Dcu) are genetically and functionally distinct from the aerobic system (Dct).
Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg-Universität, Mainz, Germany.
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D000332:Aerobiosis; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001224:Aspartic Acid / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D029382:Dicarboxylic Acid Transporters; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005650:Fumarates / Q000378:metabolism*; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D012097:Repressor Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; C414535:DcuA dicarboxylate transporter, bacteria; D029382:Dicarboxylic Acid Transporters; D029968:Escherichia coli Proteins; D005650:Fumarates; D008565:Membrane Proteins; C084955:PdhR protein, E coli; D012097:Repressor Proteins; D013386:Succinates; D014157:Transcription Factors; C086256:dcuB protein, E coli; D001224:Aspartic Acid; C032005:fumaric acid; D019802:Succinic Acid