Escherichia coli possesses two homologous anaerobic C4-dicarboxylate membrane transporters (DcuA and DcuB) distinct from the aerobic dicarboxylate transport system (Dct)

Abstract

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).

Determination of the transcriptome of Vibrio cholerae during intraintestinal growth and midexponential phase in vitro

“…These included genes encoding transporters of carbohydrates, organic acids, cations, peptides, amino acids, purines, and pyrimidines. The three anaerobic C4-dicarboxylate transporter genes (dcuABC) were among these and are consistent with the anaerobic scavenging of fumarate (20,21). There was also a clear trend suggesting that genes involved in iron acquisition were highly expressed in vivo.…”

The VC1777–VC1779 proteins are members of a sialic acid-specific subfamily of TRAP transporters (SiaPQM) and constitute the sole route of sialic acid uptake in the human pathogen Vibrio cholerae

“…Three more genes, vc2699, vcA0205 and vcA0665, in V. cholerae N16961 encode putative DcuABC family proteins that clustered with the anaerobic C 4 -dicarboxylate transporter of E. coli (N. Chowdhury & E. F. Boyd, unpublished data; Six et al, 1994;Zientz et al, 1996). In Pseudomonas aeruginosa, DctA (PA1183) and DctPQM (PA6167-PA5169) systems co-ordinately work for C 4 -dicarboxylate uptake (Valentini et al, 2011).…”

Regulation of tartrate metabolism by TtdR and relation to the DcuS–DcuR-regulated C4-dicarboxylate metabolism of Escherichia coli

“…Fumarate is the substrate for fumarate respiration, which produces succinate as the end product. Fumarate is taken up by the fumarate/succinate antiporter DcuB (dcuB gene) and reduced to succinate by fumarate reductase FrdABCD (frdABCD genes) (Cole et al, 1985;Engel et al, 1994;Golby et al, 1998;Miles & Guest, 1984, 1987Six et al, 1994;Unden & Kleefeld, 2004). C 4 -dicarboxylates, such as L-malate, D-tartrate and aspartate, are transported by the same transporter, DcuB.…”