TCDB is operated by the Saier Lab Bioinformatics Group

2.A.42 The Hydroxy/Aromatic Amino Acid Permease (HAAAP) Family

The HAAAP family includes three well-characterized aromatic amino acid:H+ symport permeases of E. coli: a high affinity tryptophan-specific permease, Mtr, a low affinity tryptophan permease, TnaB, and a tyrosine-specific permease, TyrP, as well as two well-characterized hydroxy amino acid permeases, the serine permease, SdaC, of E. coli, and the threonine permease, TdcC, of E. coli. It also includes a cysteine uptake porter, CyuP (YhaO). These proteins possess 403-443 amino acyl residues and exhibit eleven putative or established TMSs. They all function in amino acid uptake. Homologues are present in a large number of Gram-negative and Gram-positive bacteria. These proteins exhibit topological features common to the eukaryotic amino acid/auxin permease (AAAP) family (TC #2.A.18), and they exhibit limited sequence similarity with some of them. Since members of the HAAAP family exhibit limited sequence similarity with the large APC family (TC #2.A.3), all of these proteins may be related.

SdaC of E. coli (TC #2.A.42.2.1) is also called DcrA, and together with a periplasmic protein DcrB (P37620), it has been reported to play a role in phage DNA uptake in conjunction with an outer membrane receptor of the OMR family (TC #1.B.14). Thus, FhuA (TC #1.B.14.1.4) transports phage T5 DNA while BtuB (TC #1.B.14.3.1) transports phage C1 DNA (Samsonov et al., 2002). DcuB is a putative lipoprotein found only in enteric bacteria.

The generalized transport reaction catalyzed by proteins of the HAAAP family is:

Amino acid (out) + nH+ (out) → Amino acid (in) + nH+ (in).


This family belongs to the: APC Superfamily.

References associated with 2.A.42 family:

Goss, T.J., H.P. Schweizer, and P. Datta. (1988). Molecular characterization of the tdc operon of Escherichia coli K-12. J. Bacteriol. 170: 5352-5359. 3053659
Katayama, T., H. Suzuki, T. Koyanagi, and H. Kumagai. (2002). Functional analysis of the Erwinia herbicola tutB gene and its product. J. Bacteriol. 184: 3135-3141. 12003958
Loddeke, M., B. Schneider, T. Oguri, I. Mehta, Z. Xuan, and L. Reitzer. (2017). Anaerobic Cysteine Degradation and Potential Metabolic Coordination in Salmonella enterica and Escherichia coli. J. Bacteriol. 199:. 28607157
Samsonov, V.V., V.V. Samsonov, and S.P. Sineoky. (2002). DcrA and dcrB Escherichia coli genes can control DNA injection by phages specific for BtuB and FhyA receptors. Res. Microbiol. 153: 639-646. 12558182
Sarsero, J.P. and A.J. Pittard. (1995). Membrane topology analysis of Escherichia coli K-12 Mtr permease by alkaline phosphatase and β-galactosidase fusions. J. Bacteriol. 177: 297-306. 7814318
Sarsero, J.P., P.J. Wookey, P. Gollnick, C. Yanofsky, and A.J. Pittard. (1991). A new family of integral membrane proteins involved in transport of aromatic amino acids in Escherichia coli. J. Bacteriol. 173: 3231-3234. 2022620
Shao, Z-Q, R.T. Lin, and E.B. Newman. (1994). Sequencing and characterization of the sdaCgene and identification of the sdaCBoperon in Escherichia coli K-12. Eur. J. Biochem. 222: 901-907. 8026499
Wookey, P.J. and A.J. Pittard. (1988). DNA sequence of the gene (tyrP) encoding the tyrosine-specific transport system of Escherichia coli. J. Bacteriol. 170: 4946-4949. 3049553
Zhao, Z., J.Y. Ding, W.H. Ma, N.Y. Zhou, and S.J. Liu. (2012). Identification and characterization of γ-aminobutyric acid uptake system GabPCg (NCgl0464) in Corynebacterium glutamicum. Appl. Environ. Microbiol. 78: 2596-2601. 22307305