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Open Access Research article

Identification of a novel lipin homologue from the parasitic protozoan Trypanosoma brucei

Michel Pelletier*, Alyssa S Frainier, Dominic N Munini, Jenna M Wiemer, Amber R Karpie and Jeff J Sattora

Author Affiliations

Department of Biology, The College at Brockport, State University of New York, Brockport, NY, USA

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BMC Microbiology 2013, 13:101  doi:10.1186/1471-2180-13-101

Published: 8 May 2013

Abstract

Background

Arginine methylation is a post-translational modification that expands the functional diversity of proteins. Kinetoplastid parasites contain a relatively large group of protein arginine methyltransferases (PRMTs) compared to other single celled eukaryotes. Several T. brucei proteins have been shown to serve as TbPRMT substrates in vitro, and a great number of proteins likely to undergo methylation are predicted by the T. brucei genome. This indicates that a large number of proteins whose functions are modulated by arginine methylation await discovery in trypanosomes. Here, we employed a yeast two-hybrid screen using as bait the major T. brucei type I PRMT, TbPRMT1, to identify potential substrates of this enzyme.

Results

We identified a protein containing N-LIP and C-LIP domains that we term TbLpn. These domains are usually present in a family of proteins known as lipins, and involved in phospholipid biosynthesis and gene regulation. Far western and co-immunoprecipitation assays confirmed the TbPRMT1-TbLpn interaction. We also demonstrated that TbLpn is localized mainly to the cytosol, and is methylated in vivo. In addition, we showed that, similar to mammalian and yeast proteins with N-LIP and C-LIP domains, recombinant TbLpn exhibits phosphatidic acid phosphatase activity, and that two conserved aspartic acid residues present in the C-LIP domain are critical for its enzymatic activity.

Conclusions

This study reports the characterization of a novel trypanosome protein and provides insight into its enzymatic activity and function in phospholipid biosynthesis. It also indicates that TbLpn functions may be modulated by arginine methylation.

Keywords:
Kinetoplastid; Lipin; Arginine methylation; Phosphatidic acid phosphatase