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The phosphoarginine energy-buffering system of Trypanosoma brucei is essential and involves multiple arginine kinase isoforms with different subcellular locations.

Voncken, Frank; Gao, Fei; Wadforth, Cath; Harley, Maggie; Colasante, Claudia

Authors

Frank Voncken F.Voncken@hull.ac.uk

Fei Gao

Cath Wadforth

Maggie Harley

Claudia Colasante



Abstract

Phosphagen energy-buffering systems play an essential role in regulating the cellular energy homeostasis in periods of high-energy demand or energy supply fluctuations. Here we describe the phosphoarginine/arginine kinase system of the kinetoplastid parasite Trypanosoma brucei, consisting of three highly similar arginine kinase isoforms (TbAK1-3). Immunofluorescence microscopy using myc-tagged protein versions revealed that each isoform is located in a specific subcellular compartment: TbAK1 is exclusively found in the flagellum, TbAK2 in the glycosome, and TbAK3 in the cytosol of T. brucei. The flagellar locationof TbAK1 is dependent on a 22 amino acid long N-terminal sequence, which is sufficient for targeting a GFP-fusion protein to the trypanosome flagellum.  The glycosomal location of TbAK2 is in agreement with the presence of a conserved peroxisomal targeting signal, the C-terminal tripeptide 'SNL'.  TbAK3 lacks any apparent targeting sequences and is accordingly located in the cytosol of the parasite.  Northern blot analysis indicated that each TbAK isoform is differentially expressed in bloodsteam and procyclic forms of T. brucei, while the total cellular arginine kinase activity was 3-fold higher in bloodsteam form trypanosomes.  These results suggest a substantial change in the temporal and spatial energy requirements during parasite differentiation.  Increased arginine kinase activity improved growth of procyclic form T. brucei during oxidative challenges with hydrogen peroxide.  Elimination of the total cellular arginine kinase activity by RNA interference significantly decreased growth (>90%) of procyclic form T. brucei under standard culture conditions and was lethal for this life cycle stage in the presence of hydrogen peroxide.  The putative physiological roles fo the different TbAK isoforms in T. brucei are further discussed.

Journal Article Type Article
Publication Date Jun 11, 2013
Journal PLoS ONE
Print ISSN 1932-6203
Electronic ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 8
Issue 6
Article Number e65908
Pages e65908
APA6 Citation Voncken, F., Gao, F., Wadforth, C., Harley, M., & Colasante, C. (2013). The phosphoarginine energy-buffering system of Trypanosoma brucei is essential and involves multiple arginine kinase isoforms with different subcellular locations. PloS one, 8(6), e65908. doi:10.1371/journal.pone.0065908
DOI https://doi.org/10.1371/journal.pone.0065908
Keywords General Biochemistry, Genetics and Molecular Biology; General Agricultural and Biological Sciences; General Medicine
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