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Comparative analysis of editosome proteins in trypanosomatids.

ABSTRACT: Detailed comparisons of 16 editosome proteins from Trypanosoma brucei, Trypanosoma cruzi and Leishmania major identified protein motifs associated with catalysis and protein or nucleic acid interactions that suggest their functions in RNA editing. Five related proteins with RNase III-like motifs also contain a U1-like zinc finger and either dsRBM or Pumilio motifs. These proteins may provide the endoribonuclease function in editing. Two other related proteins, at least one of which is associated with U-specific 3' exonuclease activity, contain two putative nuclease motifs. Thus, editosomes contain a plethora of nucleases or proteins presumably derived from nucleases. Five additional related proteins, three of which have zinc fingers, each contain a motif associated with an OB fold; the TUTases have C-terminal folds reminiscent of RNA binding motifs, thus indicating the presence of numerous nucleic acid and/or protein binding domains, as do the two RNA ligases and a RNA helicase, which provide for additional catalytic steps in editing. These data indicate that trypanosomatid RNA editing is orchestrated by a variety of domains for catalysis, molecular interaction and structure. These domains are generally conserved within other protein families, but some are found in novel combinations in the editosome proteins.

SUBMITTER: Worthey EA

PROVIDER: S-EPMC275564 | biostudies-literature | 2003 Nov

REPOSITORIES: biostudies-literature

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Comparative analysis of editosome proteins in trypanosomatids.

Worthey Elizabeth A EA Schnaufer Achim A Mian I Saira IS Stuart Kenneth K Salavati Reza R

Nucleic acids research 20031101 22

Detailed comparisons of 16 editosome proteins from Trypanosoma brucei, Trypanosoma cruzi and Leishmania major identified protein motifs associated with catalysis and protein or nucleic acid interactions that suggest their functions in RNA editing. Five related proteins with RNase III-like motifs also contain a U1-like zinc finger and either dsRBM or Pumilio motifs. These proteins may provide the endoribonuclease function in editing. Two other related proteins, at least one of which is associated ...[more]

PMID: 14602897

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Project description:BackgroundProteins are composed of one or more amino acid chains and exhibit several structure levels. IDPs (intrinsically disordered proteins) represent a class of proteins that do not fold into any particular conformation and exist as dynamic ensembles in their native state. Due to their intrinsic adaptability, IDPs participate in many regulatory biological processes, including parasite immune escape. Using the information from trypanosomatids proteomes, we developed a pipeline for the identification, characterization and analysis of IDPs. The pipeline employs six disorder prediction methodologies and integrates structural and functional annotation information, subcellular location prediction and physicochemical properties. At the core of the IDP pipeline, there is a relational database that describes the protein disorder knowledge in a logically consistent manner.ResultsThe results obtained from the IDP pipeline showed that Leishmania and Trypanosoma species have approximately 70% and 55% IDPs, respectively. Our results indicate that IDPs in trypanosomatids contain disorder-promoting amino acids and order-promoting amino acids. The functional annotation analysis demonstrated enrichment of selected Gene Ontology terms. A relevant association was observed between the disordered residue numbers within predicted IDPs and their subcellular location, lack of transmembrane domains and lack of predicted function. We validated our computational findings with 2D electrophoresis designed for IDP identification and found that 100% of the identified protein spots were predicted in silico.ConclusionsBecause there is no pipeline or database addressing IDPs in trypanosomatids, the pipeline described here represents the first attempt to establish possible correlations between protein function and structural disorder in these eukaryotes. Interestingly, all significant associations detected in the contingency analysis were observed when the protein disorder content reached approximately 40%. The exploratory data analysis allowed us to develop hypotheses regarding the IDPs' association with key biological features of these parasites, including transcription and transcriptional regulation, RNA processing and splicing, and cytoskeleton.

Project description:BackgroundRecent studies have provided extensive evidence for multitudes of non-coding RNA (ncRNA) transcripts in a wide range of eukaryotic genomes. ncRNAs are emerging as key players in multiple layers of cellular regulation. With the availability of many whole genome sequences, comparative analysis has become a powerful tool to identify ncRNA molecules. In this study, we performed a systematic genome-wide in silico screen to search for novel small ncRNAs in the genome of Trypanosoma brucei using techniques of comparative genomics.ResultsIn this study, we identified by comparative genomics, and validated by experimental analysis several novel ncRNAs that are conserved across multiple trypanosomatid genomes. When tested on known ncRNAs, our procedure was capable of finding almost half of the known repertoire through homology over six genomes, and about two-thirds of the known sequences were found in at least four genomes. After filtering, 72 conserved unannotated sequences in at least four genomes were found, 29 of which, ranging in size from 30 to 392 nts, were conserved in all six genomes. Fifty of the 72 candidates in the final set were chosen for experimental validation. Eighteen of the 50 (36%) were shown to be expressed, and for 11 of them a distinct expression product was detected, suggesting that they are short ncRNAs. Using functional experimental assays, five of the candidates were shown to be novel H/ACA and C/D snoRNAs; these included three sequences that appear as singletons in the genome, unlike previously identified snoRNA molecules that are found in clusters. The other candidates appear to be novel ncRNA molecules, and their function is, as yet, unknown.ConclusionsUsing comparative genomic techniques, we predicted 72 sequences as ncRNA candidates in T. brucei. The expression of 50 candidates was tested in laboratory experiments. This resulted in the discovery of 11 novel short ncRNAs in procyclic stage T. brucei, which have homologues in the other trypansomatids. A few of these molecules are snoRNAs, but most of them are novel ncRNA molecules. Based on this study, our analysis suggests that the total number of ncRNAs in trypanosomatids is in the range of several hundred.

Project description:BackgroundThe trypanosomatids Leishmania major, Trypanosoma brucei and Trypanosoma cruzi cause some of the most debilitating diseases of humankind: cutaneous leishmaniasis, African sleeping sickness, and Chagas disease. These protozoa possess complex life cycles that involve development in mammalian and insect hosts, and a tightly coordinated cell cycle ensures propagation of the highly polarized cells. However, the ways in which the parasites respond to their environment and coordinate intracellular processes are poorly understood. As a part of an effort to understand parasite signaling functions, we report the results of a genome-wide analysis of protein kinases (PKs) of these three trypanosomatids.ResultsBioinformatic searches of the trypanosomatid genomes for eukaryotic PKs (ePKs) and atypical PKs (aPKs) revealed a total of 176 PKs in T. brucei, 190 in T. cruzi and 199 in L. major, most of which are orthologous across the three species. This is approximately 30% of the number in the human host and double that of the malaria parasite, Plasmodium falciparum. The representation of various groups of ePKs differs significantly as compared to humans: trypanosomatids lack receptor-linked tyrosine and tyrosine kinase-like kinases, although they do possess dual-specificity kinases. A relative expansion of the CMGC, STE and NEK groups has occurred. A large number of unique ePKs show no strong affinity to any known group. The trypanosomatids possess few ePKs with predicted transmembrane domains, suggesting that receptor ePKs are rare. Accessory Pfam domains, which are frequently present in human ePKs, are uncommon in trypanosomatid ePKs.ConclusionTrypanosomatids possess a large set of PKs, comprising approximately 2% of each genome, suggesting a key role for phosphorylation in parasite biology. Whilst it was possible to place most of the trypanosomatid ePKs into the seven established groups using bioinformatic analyses, it has not been possible to ascribe function based solely on sequence similarity. Hence the connection of stimuli to protein phosphorylation networks remains enigmatic. The presence of numerous PKs with significant sequence similarity to known drug targets, as well as a large number of unusual kinases that might represent novel targets, strongly argue for functional analysis of these molecules.

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Comparative analysis of editosome proteins in trypanosomatids.

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Comparative analysis of editosome proteins in trypanosomatids.

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