Steiner, Jürgen M.

062-067

Cyanophora paradoxa, cyanelle isolation, protein translocation

The living fossil Cyanophora paradoxa (Glaucocystophyta) is an obligatorily photoautotrophic biflagellated protist containing cyanelles (muroplasts), peculiar plastids surrounded by a peptidoglycan wall. This special feature likely is the strongest hint for an endosymbiotic origin of plastids from a cyanobacterial invader. Therefore this earliest diverging photosynthetic eukaryote has served as an ideal model system to study essential aspects of plastid evolution such as protein translocation, the carbon-concentrating mechanism (CCM) and plastid division. The well-established cya-nelle in vitro protein import system allows to use them as „honorary cyanobacteria“: assembly processes of supramolecular structures such as phycobilisomes and carboxysomes thus can be studied after import of labeled nucleus-encoded precursor proteins and subsequent fractionation. In this work the growth conditions and the growth behaviour of Cyanophora paradoxa under various conditions as well as the isolation of import-competent cyanelles is described.