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Office:
350 Coverdell Center
706-542-4736s
smoreno@cb.uga.edu
Lab:
360 Coverdell Center
706-583-0181
Lab Homepage
Research Overview
Research in my
laboratory centers on the characterization of calcium homeostasis pathways in Toxoplasma
gondii and
trypanosomes. We discovered a new organelle, which we named the acidocalcisome
because of its acidity and large content of calcium. While characterizing the
composition and function of this organelle we found that it contains large
amounts of phosphorus in the form of polyphosphate and they were similar to the
previously described as "polyphosphate bodies". Acidocalcisomes have now been
shown to be lysosome-related organelles and found in bacteria as well as in
mammalian cells.
One of the
acidocalcisome markers, the vacuolar-H+-pyrophosphatase also
localizes to a novel compartment in Toxoplasma gondii with similar composition and
function to the plant vacuole, which we named plant-like vacuole (PLV). This
organelle contains a vacuolar-H+-pyrophosphatase, 2 aquaporins or
water channels, a vacuolar-H+-ATPase, other transporters and
hydrolases. Experimental evidence indicates that this organelle is linked to
the endosomal pathway of the parasite and may be also involved in storing
important enzymes used for the maturation of secretory proteins. We are
presently studying the functions and biogenesis of this organelle.
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| T. gondii tachyzoites labeled with antibodies against the Vacuolar-H+-pyrophosphatase and the Cathepsin L. They both co-localize to a novel vacuolar compartment. |
We are also interested in the isoprenoid pathway of Toxoplasma gondii. Work in collaboration with other laboratories is centered on testing isoprenoid pathway inhibitors against Toxoplasma growth in vitro and in vivo. Isoprenoids are an extensive group of natural products with diverse structures consisting of various numbers of five carbon isopentenyl diphosphate (IPP) units. A central enzyme in the pathway, the farnesyl diphosphate synthase (FPPS) catalyzes the formation of farnesyl diphosphate (FPP), a precursor of critical molecules of fundamental biological functions such as dolichols, heme a, cholesterol, farnesylated proteins and others. This enzyme is a validated target for drugs and bisphosphonates, which are specific FPPS inhibitors, inhibit parasite growth in vitro and in vivo. Our hypothesis is that the isoprenoid pathway constitutes a major novel target for the treatment of toxoplasmosis.
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| Live T. cruzi epimastigotes expressing the Green Fluorescent protein gene fused with the TcPI-PLC gene. |
In Trypanosoma cruzi, the etiologic agent of Chagas' disease we characterized a novel phosphoinositide phospholipase C (TcPI-PLC), which is the only known PI-PLC that is lipid modified by N-myristoylation and S-palmitoylation and could represent the first member of a new group of PI-PLCs. In addition, the enzyme is developmentally regulated and its expression and intracellular activity is induced during the differentiation of trypomastigotes to amastigotes. TcPI-PLC associates to the outer surface of the plasma membrane of amastigotes. We are investigating the role of this enzyme in the interaction of T. cruzi with its host cell.
Representative Publications
Martins V.P., Okura M., Maric D., Engman D.M., Vieira M., Docampo R., Moreno S.N. Acylation-dependent export of Trypanosoma cruzi phosphoinositide-specific phospholipase C to the outer surface of amastigotes. (2010) J. Biol. Chem., in press.
Martins, V.P., Galizzi, M., Docampo, R., and Moreno, S.N.J. Developmental expression of a Trypanosoma cruzi phosphoinositide-specific phospholipase C in amastigotes and stimulation of host phosphoinositide hydrolysis. (2010) Inf. Immun., in press.
Miranda, K.#, Pace, D.A.#, Cintron, R., Rodrigues, J.C.F., Fang, J., Smith, A., Rohloff, P., Coelho, E., de Haas, F., de Souza, W., Coppens, I., Sibley, L.D., and Moreno, S.N.J. Characterization of a novel organelle in Toxoplasma gondii with similar composition and function to the plant vacuole. (2010) Mol. Microbiol. 7(6) 1358-1375. # Both authors contributed equally. This article was featured on the cover and commented: Novel vacuoles in Toxoplasma. van Dooren GG, Ralph SA. Mol Microbiol. (2010) 76(6):1335-9.
Miranda, K. de Souza, W. Plattner, H. Hentschel, J. Kawazoe, U. and Moreno, SNJ. Acidocalcisomes in Apicomplexan parasites (2008) Exp. Parasitol. Special issue. 118:2-9. This article was featured on the cover.
Ling Y, Li ZH, Miranda K, Oldfield E, Moreno, S.N.J. The farnesyl diphosphate/geranylgeranyl diphosphate synthase of Toxoplasma gondii is a bifunctional enzyme and the molecular target of bisphosphonates (2007) J. Biol. Chem. 282:30804-16.
Harper, J.M., Huynh, M.H., COppens, I., Parussini, F., Moreno, S.N., Carruthers, V.B. A Cleavable Propeptide Influences Toxoplasma Infection by Facilitating the Trafficking and Secretion of the TgMIC2-M2AP Invasion Complex. (2006) Mol. Biol. Cell. 17(10):4551-63.
Okura M, Fang J, Salto ML, Singer RS, Docampo R, Moreno S.N.J. A lipid-modified phosphoinositide-specific phospholipase C (TcPI-PLC) is involved in differentiation of trypomastigotes to amastigotes of Trypanosoma cruzi. (2005) J. Biol. Chem. 280:16235-43.
Docampo, R., de Souza, W., Miranda, K., Rohloff, R., and Moreno, S.N.J. (2005) Acidocalcisomes –conserved from bacteria to man. Nat. Rev. Microbiol. 3:251-261. This article was featured on the cover.
Luo, S., Ruiz, F.A., and Moreno, S.N.J. The acidocalcisome Ca2+-ATPase (TgA1) of Toxoplasma gondii is required for polyphosphate storage, intracellular calcium homeostasis and virulence. (2005) Mol. Microbiol. 55:1034-1045.
Arrizabalaga, G., Ruiz, F., Moreno, S.N.J. and Boothroyd, J.A. Ionophore-resistant mutant of Toxoplasma gondii reveals involvement of a sodium/hydrogen exchanger in calcium regulation. (2004) J. Cell Biol. 165:653-662.
Seufferheld, M.,
Vieira, M.C.F., Ruiz, F.A., Rodrigues, C.O., Moreno, S.N.J., and Docampo, R. Identification in
bacteria of organelles similar to acidocalcisomes of unicellular eukaryotes.
(2003) J.
Biol. Chem., 278, 29971-29978. This article was featured in:
Hurtley,
S.M. (2003) How different are we? Editor's Choice section. Science 300, 2005; Knight,
J. (2003) Discovery changes view of bacteria, Nature, 423, 909; Whitehouse,
D. (2003) Ancient organism challenges cell evolution. BBC News 20 June (http://news.bbc.co.uk/1/hi/sci/tech/3003946.stm).
Rodrigues, C.O., Ruiz, F.A., Rohloff, P., Scott, D.A., and Moreno, S.N.J. Characterization of isolated acidocalcisomes from Toxoplasma gondii tachyzoites reveals a novel pool of hydrolysable polyphosphate. (2002) J. Biol. Chem. 277, 48650-48656.
Shuhong L., Vieira, M. A., Zhong, L, Graves, J., and Moreno S.N.J. Cloning, functional expression and co-localization of the vacuolar Ca2+-ATPase with a vacuolar H+-pyrophosphatase to acidocalcisomes of Toxoplasma gondii. (2000) EMBO J. 20, 55-64.