Expression of alpha- and beta-Tubulin Genes during Growth of Trypanosoma cruzi Epimastigotes

Abstract

The expression of tubulin genes was studied during the growth of epimastigotes of Trypanosoma cruzi. Northern blot analysis showed that there was a decrease in the levels of alpha- and beta-tubulin mRNAs as epimastigotes changed from the logarithmic to the stationary phase. The changes were associated with a similar decrease in the rates of transcription for both of these genes as measured by run-on assays using permeabilized parasites. In contrast to these results, ubiquitin transcription increased slightly. The levels of alpha-tubulin protein per parasite also decreased in stationary compared with logarithmic phase epimastigotes, in close agreement with the decrease in transcription. However, beta-tubulin protein levels did not change significantly. Our results thus indicated that during the growth of epimastigotes, the expression of alpha-tubulin is controlled partially at the transcriptional level. On the other hand, the experiments also suggested that beta-tubulin expression is controlled at a post-transcriptional level.