Biochemical characterization of serine transport in Leishmania (Leishmania) amazonensis

Autor(es)

dos Santos, Marcos Gonzaga ^[1] ; Paes, Lisvane Silva ^[2] ; Zampieri, Ricardo Andrade ^[1] ; Laranjeira da Silva, Maria Fernanda ^[1] ; Silber, Ariel Mariano ^[2] ; Floeter-Winter, Lucile Maria ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biociencias, Dept Fisiol, BR-05508900 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Ciencias Biomed, Dept Parasitol, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Molecular and Biochemical Parasitology; v. 163, n. 2, p. 107-113, Feb. 2009.
• Área do conhecimento: Ciências Biológicas - Bioquímica
• Citações Web of Science: 6
• Assunto(s): Protozoa Leishmania mexicana Fosfatidilserinas Esfingolipídeos

Resumo

In addition to its role as a protein component in Leishmania, serine is also a precursor for the synthesis of both phosphatidylserine, which is a membrane molecule involved in parasite invasion and inactivation of macrophages, and sphingolipids, which are necessary for Leishmania to differentiate into its infective forms. We have characterized serine uptake in both promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. In promastigotes, kinetic data show a single, saturable transport system, with a Km of 0.253 ± 0.01 mM and a maximum velocity of 0.246 ± 0.04 nmol/min per 107 cells. Serine transport increased linearly with temperature in the range from 20 °C to 45 °C, allowing the calculation of an activation energy of 7.09 kJ/mol. Alanine, cysteine, glycine, threonine, valine and ethanolamine competed with the substrate at a ten-fold excess concentration. Serine uptake was dependent on pH, with an optimum activity at pH 7.5. The characterization of the serine transport process in amastigotes revealed a transport system with a similar Km, energy of activation and pH response to that found in promastigotes, suggesting that the same transport system is active in both insect vector and mammalian host Leishmania stages. This could constitute an evolutionary mechanism that guarantees the provision of such an essential molecule during host change events, such as differentiation into amastigotes and macrophage invasion, as well as to ensure that the parasite maintains the infection in the mammalian host. (AU)

• Processo FAPESP: 06/00019-0 - Aspectos bioquímicos e fisiológicos na infecção por Leishmania
• Beneficiário: Lucile Maria Floeter-Winter
• Modalidade de apoio: Auxílio à Pesquisa - Temático