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The singular properties of photosynthetic cytochrome c 550 from the diatom Phaeodactylum tricornutum suggest new alternative functions
Author(s) -
BernalBayard Pilar,
Álvarez Consolación,
Calvo Purificación,
Castell Carmen,
Roncel Mercedes,
Hervás Manuel,
Navarro José A.
Publication year - 2019
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12888
Subject(s) - phaeodactylum tricornutum , phycobilisome , cytochrome b6f complex , biology , thylakoid , chloroplast , photosynthesis , cytochrome , diatom , cytochrome c , photosystem ii , algae , cytochrome f , thalassiosira pseudonana , biochemistry , botany , cyanobacteria , photosystem i , phytoplankton , mitochondrion , bacteria , ecology , genetics , nutrient , gene , enzyme
Cytochrome c 550 is an extrinsic component in the luminal side of photosystem II (PSII) in cyanobacteria, as well as in eukaryotic algae from the red photosynthetic lineage including, among others, diatoms. We have established that cytochrome c 550 from the diatom Phaeodactylum tricornutum can be obtained as a complete protein from the membrane fraction of the alga, although a C‐terminal truncated form is purified from the soluble fractions of this diatom as well as from other eukaryotic algae. Eukaryotic cytochromes c 550 show distinctive electrostatic features as compared with cyanobacterial cytochrome c 550 . In addition, co‐immunoseparation and mass spectrometry experiments, as well as immunoelectron microscopy analyses, indicate that although cytochrome c 550 from P. tricornutum is mainly located in the thylakoid domain of the chloroplast – where it interacts with PSII – , it can also be found in the chloroplast pyrenoid, related with proteins linked to the CO 2 concentrating mechanism and assimilation. These results thus suggest new alternative functions of this heme protein in eukaryotes.