title: Ejectisins: tough and tiny polypeptides are a major component of cryptophycean ejectisomes.
abstract: Fragments of discharged ejectisomes were isolated from two Cryptomonas and a Chroomonas species by detergent treatment followed by Percoll density gradient centrifugation. The fragments withstand high concentrated detergent solutions, reducing agents and freeze-thawing. Disintegration was achieved in 6 M guanidine hydrochloride. Reassembly into long, filamentous, ejectisome-like structures occurred after dialysis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the polypeptide patterns of isolated ejectisome fragments and of reconstituted ejectisome-like structures were dominated by polypeptides with relative molecular weights of approximately 6 kDa. The polypeptides were not glycosylated and did not cross-react with antisera directed against recombinant Reb polypeptides which constitute the R-bodies of Caedibacter taeniospiralis. A polyclonal antiserum directed against reconstituted, ejectisome-like filaments cross-reacted with the 6-kDa polypeptides and immunolabeled extruded ejectisome filaments. Twenty amino acid residues, obtained by N-terminal amino acid sequence analysis, matched to polypeptide sequences deduced from cDNA sequences of the cryptophyte Guillardia theta. The term "ejectisins" is introduced for the 6-kDa polypeptides which represent a major component of cryptophycean ejectisomes.
authors.affiliation: Planktologie, ICBM, Carl-von-Ossietzky-Universität Oldenburg, P.O.B. 2503, 26129, Oldenburg, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Ammermann
authors.forename: Tristan
authors.initials: T
authors.lastname: Schneider
authors.forename: Martin
authors.initials: M
authors.lastname: Westermann
authors.forename: Helmut
authors.initials: H
authors.lastname: Hillebrand
authors.forename: Erhard
authors.initials: E
authors.lastname: Rhiel
mesh_terms: D002478:Cells, Cultured; D044785:Cryptophyta / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010455:Peptides / Q000378:metabolism*
chemical_list: D010455:Peptides