Trypanosoma Brucei Mitocarta And Its Expression Regulation

Trypanosomiasis is causing serious damage to human health and economic development, and hasbeen listed by the World Health Organization as one of the major infectious diseases that are the focusof intense efforts to control or eliminate. As the genome projects of protozoan parasites are in progress,genomes of three representative parasites causing fatal disease to human (including Trypanosomabrucei, Trypanosoma cruzi and Leishmania major) have been sequenced, providing both opportunitiesand challenges for post-genomic research of Trypanosome. Post-genomic research aims to learn genefunctions and corresponding mechanisms, in which proteomics research is an important aspect. In thisthesis, T. brucei mitochondrial proteomics are studied based on both bioinformatics and biologicalexperiments, including the T. brucei mitochondrial proteome composition, differential expressionduring its life cycle and the corresponding regulation mechanism. The main research works andinnovative results are summarized as follows:1. Unique biological features of T. brucei mitochondrion was illustrated based on its structure,function and biogenesis, and the mitochondrial genome was analyzed including the genome structure,nucleotide composition and gene distribution, revealing the importance of T. brucei mitochondrion inits complex life cycle and significant differences compared to other eukaryotes. This work suggeststhat mitochondrion may play an important regulatory role in the life cycle of T. brucei, thus providingthe direction of this research.2. A new approach based on a mixed feature selection algorithm was proposed to identifymitochondrial proteins. Taking multiple features which may be related to protein localization intoaccount, an SVM-based prediction model TMPP was developed based on the discriminative featuresselected by the mixed feature selection algorithm. Compared to available prediction tools, TMPPshows much better performance in recognizing T. brucei mitochondrial proteins, thus can be used topredict T. brucei mitochondrial proteome.3. The mitochondrial proteome of T. brucei was defined by using both bioinformatics andbiological experiment approaches, and the results have been incorporated into the internationalwell-known pathogen database GeneDB. The T. brucei mitochondrial proteome predicted by TMPPcotains1065proteins, and fluorescence microscopy and western blotting techniques were used tovalidate the predicted result. The experimental results strongly confirmed the reliability of thepredicted mitochondrial proteome.4. The expression profiles of T. brucei MitoCarta in three different stages were obtained by using high-throughput RNA-seq technology, and the expression regulation of T. brucei MitoCarta during itslife cycle was studied. The expression profiles of T. brucei MitoCarta during the life cycle reveal thatabout40%of the mitochondrial proteome appear to be stage-regulated, showing potential regulatoryfunctions, while~60%show stable abundance and some of them are highly expressed in all stages,indicating their potential roles in maintaining mitochondrion functions.5. Take advantage of the unique SL trans-splicing process in T. brucei, splicing sites andfrequencies of T. brucei MitoCarta in three different stages were obtained by using high-throughputRNA-seq technology. The splicing pattern and the role of splicing process in the expression regulationof T. brucei MitoCarta during life cycle were studied. The splicing pattern of T. brucei MitoCartareveals that a large number of genes are alternatively spliced and some of them change splicingpatterns during the life cycle, indicating that some splice sites are stage-specific. Study on alternativesplicing variants indicates that alternative splicing may change the localizations and functions of thecorresponding proteins, revealing that althernative splicing likely to result in dual localization of theencoded proteins from a single gene. These findings indicate that splicing process may be animportant mechanism resulting in the stage-specific expression of T. brucei MitoCarta via alternativesplicing, differential splicing and the splicing efficiency.In conclusion, the T. brucei MitoCarta and its expression regulation have been studied in this thesis,revealing the T. brucei mitochondrial proteom, its expression profiles and the correspondingregulation mechanism during life cycle. The results will be a reference to drug design againstTrypanosomiasis, and also will benefit the mitochondrial proteome research in close species.