OXPHOS system in Euglena gracilis
Euglena gracilis (A) is a secondary photosynthetic flagellate that arose from an endosymbiosis between a green alga and an ancient phagotroph. In this organism, a close relation between mitochondria and secondary plastids has been described (B). Euglenids, members of the supergroup Excavata, generally have discoidal cristae, which exhibit a paddle-like morphology (C). The subunit composition of the OXPHOS complexes among the Euglenozoa species includes the conserved canonical subunits, mainly related with the catalytic activity of each complex, but also a series of lineage-specific atypical subunits. This divergent subunit composition leads notably to the presence of atypical domains observed in the structures of complexes I, IV and V2 (D-H). Despite the presence of atypical subunit composition and additional structural domains described in Euglena complexes I, IV and V, canonical associations into III2/IV, III2/IV2 SCs and I/III2/IV respirasome were observed together with two oligomeric forms of the ATP synthase (V2 and V4) (I).
References
A) Miranda Astudillo H.V. in preparation…
B) Zimorski V., Rauch C., van Hellemond J.J., Tielens A.G.M., Martin W.F. (2017) The Mitochondrion of Euglena gracilis. In: Schwartzbach S., Shigeoka S. (eds) Euglena: Biochemistry, Cell and Molecular Biology. Advances in Experimental Medicine and Biology, vol 979. Springer, Cham. https://doi.org/10.1007/978-3-319-54910-1_2
C) https://www.sciencesource.com/Doc/TR1_WATERMARKED/3/d/9/0/SS2385360.jpg?d63642064142
D) Mühleip, A.W., E. Dewar, C., Schnaufer, A., Kühlbrandt, W., Davies, K.M., 2017. In-situ structure of trypanosomal ATP synthase dimer reveals unique arrangement of catalytic subunits. PNAS. https://doi.org/10.1073/pnas.1612386114
E) Yadav, K.N.S., Miranda-Astudillo, H. V., Colina-Tenorio, L., Bouillenne, F., Degand, H., Morsomme, P., González-Halphen, D., Boekema, E.J., Cardol, P., 2017. Atypical composition and structure of the mitochondrial dimeric ATP synthase from Euglena gracilis. Biochim. Biophys. Acta - Bioenerg. 1858, 267–275. https://doi.org/10.1016/j.bbabio.2017.01.007
F) Mühleip, A., McComas, S.E., Amunts, A., 2019. Structure of a mitochondrial ATP synthase with bound native cardiolipin. Elife 8, 1–23. https://doi.org/10.7554/eLife.51179
G) Miranda-Astudillo, H., Yadav, K.N.S., Colina-Tenorio, L., Bouillenne, F., Degand, H., Morsomme, P., Boekema, E.J., Cardol, P., 2018. The atypical subunit composition of respiratory complexes I and IV is associated with original extra structural domains in Euglena gracilis. Sci. Rep. 8, 9698. https://doi.org/10.1038/s41598-018-28039-z
H) Baradaran R., in preparation…
I) Miranda-Astudillo, H.V., Yadav, K.N.S., Boekema, E.J. et al. Supramolecular associations between atypical oxidative phosphorylation complexes of Euglena gracilis. J Bioenerg Biomembr (2021). https://doi.org/10.1007/s10863-021-09882-8