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Ubiquitin genes in trypanosomatidae
L V Kirchhoff1, K S Kim, D M Engman
1Department of Internal Medicine, University of Iowa, Iowa City 52242.
Abstract:
A ubiquitin encoding cDNA from Trypanosoma cruzi, the protozoan cause of Chagas' disease, was isolated by immunoscreening a lambda gt11 expression library with serum from a mouse chronically infected with this parasite. The cDNA encodes a precursor protein consisting of four tandem repeats of ubiquitin differing from that of Saccharomyces cerevisiae in four positions, followed by an unrelated 52-amino acid tail containing a putative metal and nucleic acid binding domain. Southern and Northern blots of DNA and RNA from various strains of T. cruzi and from several African trypanosome and Leishmania isolates revealed dramatic differences in the numbers and sizes of ubiquitin genes and transcripts. One of the T. cruzi isolates examined has as many as 10 ubiquitin genes, while a strain of Leishmania donovani appears to have only 1. Forty or more tandemly arranged ubiquitin coding repeats are present in some genes, while others have only two or three. Evidence for stage-specific expression of a ubiquitin transcript was found in one strain, but no stress-induced changes in the pattern of transcripts were detected in the one isolate examined. Thus the cellular requirements for ubiquitin in trypanosomatids can be supplied by diversely organized genes containing highly variable numbers of ubiquitin coding repeats.
Insights
Researchers isolated a ubiquitin gene from Trypanosoma cruzi, the parasite causing Chagas' disease. Gene organization and copy number vary significantly across trypanosomatid species, influencing ubiquitin production.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Ubiquitin is a crucial protein involved in cellular regulation.
- Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi.
- Understanding gene organization in parasites is vital for drug development.
Purpose of the Study:
- To isolate and characterize the ubiquitin-encoding gene from Trypanosoma cruzi.
- To investigate the diversity of ubiquitin gene organization and expression in trypanosomatids.
Main Methods:
- Immunoscreening of a lambda gt11 expression library using infected mouse serum.
- Southern and Northern blot analyses of DNA and RNA from various trypanosomatid strains.
- Sequence analysis of the isolated cDNA.
Main Results:
- A ubiquitin precursor cDNA from T. cruzi was isolated, encoding four ubiquitin repeats and a unique C-terminal tail.
- Significant variation in ubiquitin gene copy number (1-10 genes) and transcript size was observed across T. cruzi, African trypanosomes, and Leishmania species.
- Some T. cruzi genes contained over 40 repeats, while others had only 2-3.
- Stage-specific expression of a ubiquitin transcript was detected in one strain, but no stress-induced changes were found.
Conclusions:
- Trypanosomatids exhibit remarkable diversity in ubiquitin gene organization and copy number.
- This genetic variability allows trypanosomatids to meet cellular ubiquitin requirements through different gene structures.
- The findings highlight the adaptability of ubiquitin gene regulation in these parasites.