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2.A.16 The Tellurite-resistance/Dicarboxylate Transporter (TDT) Family
The TDT family includes members from the bacterial (E. coli and Haemophilus influenzae), archaeal (Methanococcus jannaschii) and eukaryotic (Schizosaccharomyces pombe) kingdoms and therefore occurs ubiquitously. Only two members of the family have been functionally characterized. One is the TehA protein of E. coli which functions as a tellurite-resistance uptake permease; the other is the Mae1 protein of S. pombe which functions in the uptake of malate and other dicarboxylates by a proton symport mechanism. These proteins are 320-350 amino acyl residues in length except for the yeast protein which is 438 residues. All exhibit 10 putative transmembrane a-helical spanners (TMSs). The phylogenetic tree for the TDT family exhibits three major branches, one for the bacterial proteins, one for the archaeal proteins and one for the yeast protein.
The transport reaction catalyzed by the TehA protein of E. coli is:
Tellurite (out) + nH+ (out) --> Tellurite (in) + nH+ (in).
The transport reaction catalyzed by the Mae1 protein of S. pombe is:
C4-Dicarboxylate (out) + nH+ (out) --> C4-Dicarboxylate (in) + nH+ (in).
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| References: |
Grobler, J., F. Bauer, R.E. Subden, and H.J.J. Van Vuuren (1995). The mae1 gene of Schizosaccharomyces pombe encodes a permease for malate and other C4 dicarboxylic acids. Yeast 11: 1485—1491.
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Saier, M.H., Jr., B.H. Eng, S. Fard, J. Garg, D.A. Haggerty, W.J. Hutchinson, D.L. Jack, E.C. Lai, H.J. Liu, D.P. Nusinew, A.M. Omar, S.S. Pao, I.T. Paulsen, J.A. Quan, M. Sliwinski, T.-T. Tseng, S. Wachi and G.B. Young (1999). Phylogenetic characterization of novel transport protein families revealed by genome analyses. Biochem. Biophys. Acta 1422: 1-56.
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Taylor, D.E., Y. Hou, R.J. Turner, and J.H. Weiner (1994). Location of a potassium tellurite resistance operon (tehA tehB) within the terminus of Escherichia coli K-12. J. Bacteriol. 176: 2740—2742.
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Walter, E.G., J.H. Weiner, and D.E. Taylor (1990). Nucleotide sequence and overexpression of the tellurite-resistance determinant from the IncHII plasmid pHH1508a. Gene 101: 1—7.
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| Examples: |
| TC# | Name | Organismal Type | Example |
| 2.A.16.1.1 | TehA tellurite resistance protein | Bacteria | TehA of E. coli |
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| 2.A.16.2.1 | Mae1 malate transport protein | Yeast | Mae1 of Schizosaccharomyces pombe |
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