Isolation and characterization of the ejectisomes of the prasinophyte Pyramimonas grossii
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For the first time, ejectisome-enriched fractions were isolated from the marine prasinophyte Pyramimonas grossii. Transmission electron microscopy revealed that most of the ejectisomes were discharged and formed long, spirally twisted filaments. Some ejectisomes were still fully or partly furled. Discharged ejectisomes measured up to 26 μm in length and 200 nm in width; those still furled measured up to 900 nm in width and 1,000 nm in length. Particle periodicities of approximately 4.2 and 5.8 nm could be measured from freeze-fractured filaments. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a protein banding pattern, dominated by polypeptides of 16–20 kDa. These polypeptides were not glycosylated and did not cross-react with antisera directed against recombinant R-body polypeptides of Caedibacter taeniospiralis or directed against reconstituted cryptophycean ejectisomes.
KeywordsEjectisome Prasinophyte Pyramimonas grossii R-body Transmission electron microscopy
The authors express their gratitude to Ms. Silke Ammermann and Ms. Susanne Linde for excellent technical assistance, and to Dr. Martina Schrallhammer (University of Dresden) for kindly providing us the recombinant R-body polypeptides of Caedibacter taeniospiralis and the antisera directed against them.
Conflict of interest
The authors declare that they have no conflict of interest.
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