Euglena gracilis and Trypanosomatids Possess Common Patterns in Predicted Mitochondrial Targeting Presequences
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Euglena gracilis possessing chloroplasts of secondary green algal origin and parasitic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi and Leishmania major belong to the protist phylum Euglenozoa. Euglenozoa might be among the earliest eukaryotic branches bearing ancestral traits reminiscent of the last eukaryotic common ancestor (LECA) or missing features present in other eukaryotes. LECA most likely possessed mitochondria of endosymbiotic α-proteobacterial origin. In this study, we searched for the presence of homologs of mitochondria-targeted proteins from other organisms in the currently available EST dataset of E. gracilis. The common motifs in predicted N-terminal presequences and corresponding homologs from T. brucei, T. cruzi and L. major (if found) were analyzed. Other trypanosomatid mitochondrial protein precursor (e.g., those involved in RNA editing) were also included in the analysis. Mitochondrial presequences of E. gracilis and these trypanosomatids seem to be highly variable in sequence length (5–118 aa), but apparently share statistically significant similarities. In most cases, the common (M/L)RR motif is present at the N-terminus and it is probably responsible for recognition via import apparatus of mitochondrial outer membrane. Interestingly, this motif is present inside the predicted presequence region in some cases. In most presequences, this motif is followed by a hydrophobic region rich in alanine, leucine, and valine. In conclusion, either RR motif or arginine-rich region within hydrophobic aa-s present at the N-terminus of a preprotein can be sufficient signals for mitochondrial import irrespective of presequence length in Euglenozoa.
KeywordsCleaved targeting sequence Euglenids Euglenozoa Excavata Kinetoplastids Mitochondrial protein import Protein motifs
This work was supported by Scientific Grant Agency of the Slovak Ministry of Education and the Academy of Sciences (grants 1/0416/09 and 1/0393/09), Comenius University Grants (UK/54/2011), Czech Science Foundation grant P506/11/1320, and is the result of the project implementation: “The Improvement of Centre of excellence for exploitation of informational biomacromolecules in improvement of quality of life,” ITMS 26240120027, supported by the Research & Development Operational Programme funded by the ERDF. This paper has been published in frame of the project “Strengthening research institutions at the University of Ostrava,” CZ.1.07/2.3.00/30.0047, which is co-financed by the European Social Fund and the state budget of the Czech Republic. We thank Dr. Broňa Brejová (Department of Computer Science, Faculty of Mathematics, Physics, and Informatics, Comenius University, Bratislava, Slovakia), Dr. Tomáš Vinař (Department of Applied Informatics, Faculty of Mathematics, Physics, and Informatics, Comenius University, Bratislava, Slovakia), and Dr. Pavel Doležal and Vojtěch Žárský (both from the Department of Parasitology, Faculty of Science, Charles University in Prague) for help with the choice of appropriate bioinformatic programs to analyze the data.
- Bailey TL, Elkan C (1994) Fitting a mixture model by expectation maximization to discover motifs in biopolymers. In: proceedings of the second international conference on intelligent systems for molecular biology, AAAI Press, Menlo Park, pp 28–36Google Scholar
- Chan Y-F, Moestrup Ø, Chang J (2012) On Keelungia pulex nov. gen. et nov. sp., a heterotrophic euglenoid flagellate that lacks pellicular plates (Euglenophyceae, Euglenida). Eur J Protistol. http://dx.doi.org/10.1016/j.ejop.2012.04.003. Accessed 13 Aug 2012
- Gasteiger E, Hoogland C, Gattiker A, Duvaud S, Wilkins MR, Appel RD, Bairoch A (2005). Protein identification and analysis tools on the ExPASy Server. In: Walker JM (ed) The proteomics protocols handbook, Humana Press, Totowa, pp 571–607Google Scholar
- Linton EW, Karnkowska-Ishikawa A, Kim JI, Shin W, Bennett MS, Kwiatowski J, Zakryś B, Triemer RE (2010) Reconstructing euglenoid evolutionary relationships using three genes: nuclear SSU and LSU, and chloroplast SSU rDNA sequences and the description of Euglenaria gen. nov. (Euglenophyta). Protist 161:603–619PubMedCrossRefGoogle Scholar
- Long S, Jirků M, Ayala FJ, Lukeš J (2008) Mitochondrial localization of human frataxin is necessary but processing is not for rescuing frataxin deficiency in Trypanosoma brucei. Proc Natl Acad Sci USA 105:1373–13468Google Scholar
- Turmel M, Gagnon M-C, O`Kelly CJ, Lemieux C (2009) The chloroplast genomes of the green algae Pyramimonas, Monomastix, and Pycnococcus shed new light on the evolutionary history of prasinophytes and the origin of the secondary chloroplasts of euglenids. Mol Biol Evol 26:631–648PubMedCrossRefGoogle Scholar