5 research outputs found
Phosphatidylcholine synthesis inCrithidia deanei : the influence of the endosymbiont
8 p. : il.In this study, the role of phospholipid biosynthetic pathways was investigated in
the establishment of the mutualistic relationship between the trypanosomatid
protozoan Crithidia deanei and its symbiotic bacterium. Although the endosymbiont
displays two unit membranes, it lacks a typical Gram-negative cell wall. As in
other intracellular bacteria, phosphatidylcholine is a major component of the
symbiont envelope. Here, it was shown that symbiont-bearing C. deanei incorporates
more than two-fold 32Pi into phospholipids as compared with the aposymbiotic
strain. The major phospholipid synthesized by both strains was
phosphatidylcholine, followed by phosphatidylethanolamine and phosphatidylinositol.
Cellular fractioning indicated that 32Pi-phosphatidylcholine is the major
phospholipid component of the isolated symbionts, as well as of mitochondria.
Although the data indicated that isolated symbionts synthesized phospholipids
independently of the trypanosomatid host, a key finding was that the isolated
bacteria synthesized mostly phosphatidylethanolamine, rather than phosphatidylcholine.
These results indicate that phosphatidylcholine production by the
symbiont depends on metabolic exchanges with the host protozoan. Insight about
the mechanisms underlying lipid biosynthesis in symbiont-bearing C. deanei
might help to understand how the prokaryote/trypanosomatid relation has
evolved in the establishment of symbiosis
Symbiont modulates expression of specific gene categories in Angomonas deanei
Trypanosomatids are parasites that cause disease in humans, animals, and plants. Most are non-pathogenic and some harbor a symbiotic bacterium. Endosymbiosis is part of the evolutionary process of vital cell functions such as respiration and photosynthesis. Angomonas deanei is an example of a symbiont-containing trypanosomatid. In this paper, we sought to investigate how symbionts influence host cells by characterising and comparing the transcriptomes of the symbiont-containing A. deanei (wild type) and the symbiont-free aposymbiotic strains. The comparison revealed that the presence of the symbiont modulates several differentially expressed genes. Empirical analysis of differential gene expression showed that 216 of the 7625 modulated genes were significantly changed. Finally, gene set enrichment analysis revealed that the largest categories of genes that downregulated in the absence of the symbiont were those involved in oxidation-reduction process, ATP hydrolysis coupled proton transport and glycolysis. In contrast, among the upregulated gene categories were those involved in proteolysis, microtubule-based movement, and cellular metabolic process. Our results provide valuable information for dissecting the mechanism of endosymbiosis in A. deanei