Tubulin biosynthesis in the developmental cycle of a parasitic protozoan, Leishmania mexicana: changes during differentiation of motile and nonmotile stages.

Abstract

Cytodifferentiation in the transmission cycle of the parasitic protozoan L. mexicana amazonensis was studied in vitro. The flagellated motile promastigotes transform into the nonmotile amastigotes in 7 days at 35.degree. C intracellularly in the murine macrophage line J774G8. In medium 199 plus fetal bovine serum, the reverse transformation occurs extracellularly at 27.degree. C in 2 days. Slab gel electrophoresis of Leishmania labeled with [35S]methionine during transformation revealed changes in protein banding patterns. The intensity of 2 protein species with apparent MW .apprxeq. 55,000 increased in the amastigote-to-promastigote differentiation and decreased during the reverse transformation. These 2 protein species comigrated approximately with .alpha.- and .beta.-tubulin of Chlamydomonas flagella in 2-dimensional gel electrophoresis. The lower band was further identified as .beta.-tubulin by immunoprecipitation using rabbit antiserum specific to the .beta.-tubulin of Chlamydomonas axonemes. The biosynthetic change of tubulin correlated with the morphological change of microtubules in leishmanial flagella and cytoskeleton during transformation.