Alpha tubulin genes from Leishmania braziliensis:genomic organization, gene structure and insights on their expression

Abstract

BackgroundAlpha tubulin is a fundamental component of the cytoskeleton which is responsible for cell shape and is involved in cell division, ciliary and flagellar motility and intracellular transport. Alpha tubulin gene expression varies according to the morphological changes suffered by Leishmania in its life cycle. However, the objective of studying the mechanisms responsible for the differential expression has resulted to be a difficult task due to the complex genome organization of tubulin genes and to the non-conventional mechanisms of gene regulation operating in Leishmania.ResultsWe started this work by analyzing the genomic organization of α-tubulin genes in the Leishmania braziliensis genome database. The genomic organization of L. braziliensis α-tubulin genes differs from that existing in the L. major and L. infantum genomes. Two loci containing α-tubulin genes were found in the chromosomes 13 and 29, even though the existence of sequence gaps does not allow knowing the exact number of genes at each locus. Southern blot assays showed that α-tubulin locus at chromosome 13 contains at least 8 gene copies, which are tandemly organized with a 2.08-kb repetition unit; the locus at chromosome 29 seems to contain a sole α-tubulin gene. In addition, it was found that L. braziliensis α-tubulin locus at chromosome 13 contains two types of α-tubulin genes differing in their 3′ UTR, each one presumably containing different regulatory motifs. It was also determined that the mRNA expression levels of these genes are controlled by post-transcriptional mechanisms tightly linked to the growth temperature. Moreover, the decrease in the α-tubulin mRNA abundance observed when promastigotes were cultured at 35°C was accompanied by parasite morphology alterations, similar to that occurring during the promastigote to amastigote differentiation.ConclusionsInformation found in the genome databases indicates that α-tubulin genes have been reorganized in a drastic manner along Leishmania speciation. In the L. braziliensis genome database, two loci containing α-tubulin sequences were found, but only the locus at chromosome 13 contains the prototypic α-tubulin genes, which are repeated in a head-to-tail manner. Also, we determined that the levels of α-tubulin mRNAs are down-regulated drastically in response to heat shock by a post-transcriptional mechanism which is dependent upon active protein synthesis.

Leishmanicidal Activities of Novel Methylseleno-Imidocarbamates

“…Interestingly, its gene expression was significantly reduced after treatment. In fact, a downregulation of alpha-tubulin mRNA levels had been described in response to stress (24). These data reinforced the abovementioned action of compounds 2b and 4b against Leishmania spp.…”

“…It is a key component of the cytoskeleton, responsible for cell shape and involved in cell division, ciliary and flagellar motility, and intracellular transport (24). Recently, alpha-tubulin has been related to drug resistance (25,26).…”

Using proteomics as a powerful tool to develop a vaccine against Mediterranean visceral leishmaniasis

“…In addition, elongation factors, heat shock proteins such as HSP70, HSP83, and other chaperones, as well as tubulin and other housekeeping proteins, have been observed. These data are in the same line with those of other studies (Moreira and Murta 2016;Ramírez et al 2013). In addition, to use these markers in the improvement of vaccines for MVL, by focusing on these proteins, we can reach more information about the biology of L. infantum.…”

Genome Plasticity in Cultured Leishmania donovani: Comparison of Early and Late Passages

“…On the contrary alpha tubulin was mostly down regulated in the later passages. Tubulin plays a very important role in cytoskeleton formation and its expression is post-transcriptionally controlled and tightly linked to parasite transformation ( Ramirez et al, 2013b ). During the infection cycle, the pathogen utilizes hosts cytoskeletal machinery for pathogenicity ( Gruenheid and Finlay, 2003 ) probably leading to less expression of these proteins.…”