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Structure of p15 trypanosome microtubule associated protein
Reuven Rasooly1, Naomi Balaban
1Department of Nutrition, University of California, Davis, One Shields Ave, Meyer Hall Room 3135, Davis, CA 95616, USA. rrasooly@whnrc.usda.gov
Abstract:
Trypanosomes are protozoan parasites, containing subpellicular microtubules that are crosslinked to one another and to the plasma membrane by unique microtubule associate proteins (MAPs). One of these MAPs, purified from the subpellicular microtubules by a tubulin affinity column, is termed p15alpha. This protein was shown to be specific to the subpellicular microtubules by immunoelectron microscopy and was also shown to induce microtubule bundling. We show here that the gene coding for p15alpha is present in multiple copies. It is 258 bp long and contains 16 highly organized 15 bp long repetitive sequences. The deduced amino acid sequence indicates that p15alpha contains 16 highly organized, nearly identical tandem repeats, with a periodicity of five amino acids, which are rich in positively charged and in non-polar (hydrophobic) amino acids. The p15 family is unique to trypanosomes and has no significant sequence homology to other species. p15 can bind both tubulin and phospholipids in vitro and is therefore hypothesized to contribute to the stability of the trypanosome subpellicular microtubules.
Insights
The p15alpha protein in trypanosomes stabilizes microtubules through unique tandem repeats. This parasite-specific protein binds tubulin and phospholipids, aiding microtubule structure.
Area of Science:
- Cell Biology
- Parasitology
- Molecular Biology
Background:
- Trypanosomes possess unique subpellicular microtubules crucial for their structure.
- These microtubules are crosslinked by specialized microtubule-associated proteins (MAPs).
- p15alpha is a MAP identified from trypanosome subpellicular microtubules, known to induce bundling.
Purpose of the Study:
- To characterize the gene and protein structure of p15alpha.
- To investigate the molecular basis of p15alpha's role in microtubule stability.
- To explore the evolutionary uniqueness of the p15 family in trypanosomes.
Main Methods:
- Gene sequencing and analysis of repetitive elements.
- Deduction of amino acid sequence and identification of repeat motifs.
- In vitro binding assays with tubulin and phospholipids.
Main Results:
- The p15alpha gene is multi-copy, 258 bp long, with 16 repetitive sequences.
- The deduced p15alpha protein contains 16 tandem repeats rich in charged and hydrophobic amino acids.
- p15alpha exhibits binding affinity for both tubulin and phospholipids in vitro.
Conclusions:
- The p15 family of MAPs is unique to trypanosomes.
- p15alpha's structure, with its tandem repeats and binding properties, suggests a role in stabilizing subpellicular microtubules.
- This protein is a potential target for understanding trypanosome structure and function.