Proteome of the secondary plastid of Euglena gracilis reveals metabolic quirks and colourful history

Anna M. G. Novák Vanclová, Martin Zoltner, Steven Kelly, Petr Soukal, Kristína Záhonová, Zoltán Füssy, ThankGod E. Ebenezer, Eva Lacová Dobáková, Marek Eliáš, Julius Lukeš, Mark C. Field, Vladimír Hampl

Posted on: 20 March 2019 , updated on: 21 March 2019

Preprint posted on 11 March 2019

A green new deal – proteomic analysis shows that the Euglena gracilis chloroplast has picked up pathways and components from a variety of unrelated organisms.

Selected by Ellis O'Neill


Euglena gracilis is a well-studied unicellular alga which has only obtained its chloroplast relatively recently. This chloroplast is derived from a green alga, related to plants, but is also not necessary for Euglena to survive, unlike in plants and most algae. This indicates that some of the key metabolic pathways are not located in the chloroplast, but we still do not know all of the proteins that are located in the chloroplast.

In this paper, the authors have identified 1,345 proteins that are specifically located in the Euglena chloroplast. These include the expected chloroplast maintenance and photosynthetic genes, but do not contain many pathways for amino acid biosynthesis, unlike in plants. The Euglena chloroplast has three membranes and this analysis indicates that only the inner membrane may be similar to plants, with only hypothetical components for new outer membrane import machinery. Excitingly, the authors identify a bacterial iron-sulphur cluster assembly pathway, acquired late in evolution from bacteria.

Future Outlook

Most of the information on chloroplasts comes from the study of plants and related green algae. By studying diverse photosynthetic organisms, we can understand much more about how chloroplasts have evolved, and how they can play different roles in diverse organisms. As proteomics becomes more powerful and transcriptomes and genomes of more diverse algae become available, more studies like this will uncover more unexpected biology.


Euglena gracilis transcriptome


Euglena proteomics


Euglena for biotechnology




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