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A surface transporter family conveys the trypanosome differentiation signal


Microbial pathogens use environmental cues to trigger the developmental events needed to infect mammalian hosts or transmit to disease vectors. The parasites causing African sleeping sickness respond to citrate or cis-aconitate (CCA) to initiate life-cycle development when transmitted to their tsetse fly vector. This requires hypersensitization of the parasites to CCA by exposure to low temperature, conditions encountered after tsetse fly feeding at dusk or dawn. Here we identify a carboxylate-transporter family, PAD (proteins associated with differentiation), required for perception of this differentiation signal. Consistent with predictions for the response of trypanosomes to CCA, PAD proteins are expressed on the surface of the transmission-competent ‘stumpy-form’ parasites in the bloodstream, and at least one member is thermoregulated, showing elevated expression and surface access at low temperature. Moreover, RNA-interference-mediated ablation of PAD expression diminishes CCA-induced differentiation and eliminates CCA hypersensitivity under cold-shock conditions. As well as being molecular transducers of the differentiation signal in these parasites, PAD proteins provide the first example of a surface marker able to discriminate the transmission stage of trypanosomes in their mammalian host.

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Figure 1: Identification and characteristics of PAD proteins.
Figure 2: PAD1 identifies stumpy forms.
Figure 3: PAD2 is cold-inducible.
Figure 4: RNAi against all PAD genes reduces differentiation.


  1. Fang, J. & McCutchan, T. F. Thermoregulation in a parasite’s life cycle. Nature 418, 742 (2002)

    Article  ADS  CAS  Google Scholar 

  2. Engstler, M. & Boshart, M. Cold shock and regulation of surface protein trafficking convey sensitization to inducers of stage differentiation in Trypanosoma brucei . Genes Dev. 18, 2798–2811 (2004)

    Article  CAS  Google Scholar 

  3. Lee, S. H., Stephens, J. L., Paul, K. S. & Englund, P. T. Fatty acid synthesis by elongases in trypanosomes. Cell 126, 691–699 (2006)

    Article  CAS  Google Scholar 

  4. Hao, Z. et al. Tsetse immune responses and trypanosome transmission: implications for the development of tsetse-based strategies to reduce trypanosomiasis. Proc. Natl Acad. Sci. USA 98, 12648–12653 (2001)

    Article  ADS  CAS  Google Scholar 

  5. Zilberstein, D. & Shapira, M. The role of pH and temperature in the development of Leishmania parasites. Annu. Rev. Microbiol. 48, 449–470 (1994)

    Article  CAS  Google Scholar 

  6. Billker, O. et al. Identification of xanthurenic acid as the putative inducer of malaria development in the mosquito. Nature 392, 289–292 (1998)

    Article  ADS  CAS  Google Scholar 

  7. Barrett, M. P. et al. The trypanosomiases. Lancet 362, 1469–1480 (2003)

    Article  Google Scholar 

  8. Fenn, K. & Matthews, K. R. The cell biology of Trypanosoma brucei differentiation. Curr. Opin. Microbiol. 10, 539–546 (2007)

    Article  CAS  Google Scholar 

  9. Szoor, B. et al. Protein tyrosine phosphatase TbPTP1: a molecular switch controlling life cycle differentiation in trypanosomes. J. Cell Biol. 175, 293–303 (2006)

    Article  CAS  Google Scholar 

  10. Tasker, M. et al. A novel selection regime for differentiation defects demonstrates an essential role for the stumpy form in the life cycle of the African trypanosome. Mol. Biol. Cell 11, 1905–1917 (2000)

    Article  CAS  Google Scholar 

  11. Vassella, E., Reuner, B., Yutzy, B. & Boshart, M. Differentiation of African trypanosomes is controlled by a density sensing mechanism which signals cell cycle arrest via the cAMP pathway. J. Cell Sci. 110, 2661–2671 (1997)

    CAS  PubMed  Google Scholar 

  12. Bruce, D. et al. The morphology of the trypanosome causing disease in man in Nyasaland. Proc. R. Soc. Lond. B 85, 423–433 (1912)

    Article  ADS  Google Scholar 

  13. Turner, C. M., Barry, J. D. & Vickerman, K. Loss of variable antigen during transformation of Trypanosoma brucei rhodesiense from bloodstream to procyclic forms in the tsetse fly. Parasitol. Res. 74, 507–511 (1988)

    Article  CAS  Google Scholar 

  14. Czichos, J., Nonnengaesser, C. & Overath, P. Trypanosoma brucei: cis-aconitate and temperature reduction as triggers of synchronous transformation of bloodstream to procyclic trypomastigotes in vitro . Exp. Parasitol. 62, 283–291 (1986)

    Article  CAS  Google Scholar 

  15. Hunt, M., Brun, R. & Kohler, P. Studies on compounds promoting the in vitro transformation of Trypanosoma brucei from bloodstream to procyclic forms. Parasitol. Res. 80, 600–606 (1994)

    Article  CAS  Google Scholar 

  16. Jacobs, S. L. & Lee, N. D. Determination of citric acid in serum and urine using Br82. J. Nucl. Med. 5, 297–301 (1964)

    CAS  PubMed  Google Scholar 

  17. Sherwin, T. & Gull, K. The cell division cycle of Trypanosoma brucei brucei: timing of event markers and cytoskeletal modulations. Phil. Trans. Roy. Soc. Lond. 323, 573–588 (1989)

    Article  ADS  CAS  Google Scholar 

  18. Shapiro, S. Z., Naessen, J., Liesegang, B., Moloo, S. K. & Magondu, J. Analysis by flow cytometry of DNA synthesis during the life cycle of African trypanosomes. Acta Trop. 41, 313–323 (1984)

    CAS  PubMed  Google Scholar 

  19. Matthews, K. R. & Gull, K. Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes. J. Cell Biol. 125, 1147–1156 (1994)

    Article  CAS  Google Scholar 

  20. Kamsteeg, E. J. et al. MAL decreases the internalization of the aquaporin-2 water channel. Proc. Natl Acad. Sci. USA 104, 16696–16701 (2007)

    Article  ADS  CAS  Google Scholar 

  21. Kirk, P. et al. CD147 is tightly associated with lactate transporters MCT1 and MCT4 and facilitates their cell surface expression. EMBO J. 19, 3896–3904 (2000)

    Article  CAS  Google Scholar 

  22. Sbicego, S. et al. The use of transgenic Trypanosoma brucei to identify compounds inducing the differentiation of bloodstream forms to procyclic forms. Mol. Biochem. Parasitol. 104, 311–322 (1999)

    Article  CAS  Google Scholar 

  23. Robertson, M. Notes on the polymorphism of Trypanosoma gambiense in the blood and its relation to the exogenous cycle in Glossina palpalis . Proc. R. Soc. Lond. B 85, 241–248 (1912)

    Article  ADS  Google Scholar 

  24. Bass, K. E. & Wang, C. C. The in vitro differentiation of pleomorphic Trypanosoma brucei from bloodstream into procyclic form requires neither intermediary nor short-stumpy stage. Mol. Biochem. Parasitol. 44, 261–270 (1991)

    Article  CAS  Google Scholar 

  25. Lythgoe, K. A., Morrison, L. J., Read, A. F. & Barry, J. D. Parasite-intrinsic factors can explain ordered progression of trypanosome antigenic variation. Proc. Natl Acad. Sci. USA 104, 8095–8100 (2007)

    Article  ADS  CAS  Google Scholar 

  26. Tusnady, G. E. & Simon, I. The HMMTOP transmembrane topology prediction server. Bioinformatics 17, 849–850 (2001)

    Article  CAS  Google Scholar 

  27. Spyropoulos, I. C., Liakopoulos, T. D., Bagos, P. G. & Hamodrakas, S. J. TMRPres2D: high quality visual representation of transmembrane protein models. Bioinformatics 20, 3258–3260 (2004)

    Article  CAS  Google Scholar 

  28. Pusnik, M. et al. Pentatricopeptide repeat proteins in Trypanosoma brucei function in mitochondrial ribosomes. Mol. Cell. Biol. 27, 6876–6888 (2007)

    Article  CAS  Google Scholar 

  29. McCulloch, R. et al. Transformation of monomorphic and pleomorphic Trypanosoma brucei . Methods Mol. Biol. 262, 53–86 (2004)

    CAS  PubMed  Google Scholar 

  30. Lanham, S. M. Separation of trypanosomes from the blood of infected rats and mice by anion-exchangers. Nature 218, 1273–1274 (1968)

    Article  ADS  CAS  Google Scholar 

  31. Field, M. C. et al. New approaches to the microscopic imaging of Trypanosoma brucei . Microsc. Microanal. 10, 621–636 (2004)

    Article  ADS  CAS  Google Scholar 

  32. Saliba, K. J. et al. Sodium-dependent uptake of inorganic phosphate by the intracellular malaria parasite. Nature 443, 582–585 (2006)

    Article  ADS  CAS  Google Scholar 

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We thank E. Ullu for the gift of genomic macroarrays, M. Engstler and M. Boshart for the gift of the AnTat1.1 90:13 line, and A. Schneider for pALC14. We thank D. Hall, P. Davies and D. Levin for technical assistance, P. MacGregor for statistical analysis and A. Paterou and D. Murray for Image analysis. This work was supported by a Wellcome Trust project grant and programme grant to K.R.M. S.D. was supported by a BBSRC studentship, a Wellcome Trust Programme Grant to K.R.M. and by a Journal of Cell Science Travelling fellowship for a visit to the laboratory of K.K. Support was also provided through a Wellcome Trust strategic award for the Centre for Immunity, Infection and Evolution and a BBSRC REI award for confocal facilities.

Author Contributions S.D. carried out all trypanosome experiments, R.M. carried out the Xenopus oocyte transport assays, K.K. contributed to the design of the transport assays, and K.R.M. conceived and supervised the study; the manuscript was written by K.R.M. and S.D.

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Correspondence to Keith R. Matthews.

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Dean, S., Marchetti, R., Kirk, K. et al. A surface transporter family conveys the trypanosome differentiation signal. Nature 459, 213–217 (2009).

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