Phylogenetic viewpoints on regulation of light harvesting and electron transport in eukaryotic photosynthetic organisms

Abstract

The comparative study of photosynthetic regulation in the thylakoid membrane of different phylogenetic groups can yield valuable insights into mechanisms, genetic requirements and redundancy of regulatory processes. This review offers a brief summary on the current understanding of light harvesting and photosynthetic electron transport regulation in different photosynthetic eukaryotes, with a special focus on the comparison between higher plants and unicellular algae of secondary endosymbiotic origin. The foundations of thylakoid structure, light harvesting, reversible protein phosphorylation and PSI-mediated cyclic electron transport are traced not only from green algae to vascular plants but also at the branching point between the ''green'' and the ''red'' lineage of photosynthetic organisms. This approach was particularly valuable in revealing processes that (1) are highly conserved between phylogenetic groups, (2) serve a common physiological role but nevertheless originate in divergent genetic backgrounds or (3) are missing in one phylogenetic branch despite their unequivocal importance in another, necessitating a search for alternative regulatory mechanisms and interactions.Keywords Cyclic/linear electron flow Á Diatoms Á Light-harvesting proteins Á Red lineage Á Reversible phosphorylation of thylakoid proteins Á PGR5 Á STN7

Rising CO2 Interacts with Growth Light and Growth Rate to Alter Photosystem II Photoinactivation of the Coastal Diatom Thalassiosira pseudonana

“…More generally we find a suggestive correlation between the diatom frustule and the low susceptibility of diatoms, as a group, to photoinactivation [31], when compared to other phytoplankton measured under comparable conditions including coccolithophores [8], [32], [33], picocyanobacteria [34], prasinophytes [35], Bolidomonas [70] and other taxa (Campbell et al unpub.). Even here, however, specificities of diatom photosystem subunit composition [71] and metabolism [65] provide alternate explanations for the unusually low susceptibility of diatoms to photoinactivation of PSII.…”

The major thylakoid protein kinases STN7 and STN8 revisited: effects of altered STN8 levels and regulatory specificities of the STN kinases

“…In contrast, under HL conditions, LHCII is preferentially released from the photosystems to participate in heat dissipation (Allakhverdiev and Murata, 2004; Murata et al, 2007; Allakhverdiev et al, 2008) and amounts of PSII supercomplexes are decreased due to increased PSII protein phosphorylation (Tikkanen et al, 2008, 2010). While studies on the role of PSII core phosphorylation in D1 turnover based on the protein kinase mutants stn8 and stn7 stn8 have led to somewhat contradictory results (Bonardi et al, 2005; Tikkanen et al, 2008; Fristedt et al, 2009), more recently the consensus has emerged that PSII phosphorylation exerts a rather indirect influence on PSII turnover via the modulation of thylakoid ultrastructure and PSII complex formation and migration (Grouneva et al, 2013). Here we show that the increased PSII core phosphorylation in oe STN8 plants (Figure 6A) indeed leads to a slight reduction in photoinhibition after long-term exposure to fluctuating HL (Figure 7A).…”

A novel type of light-harvesting antenna protein of red algal origin in algae with secondary plastids

“…There are striking differences in the regulation of photosynthesis between plants and diatoms [51,57], especially in the structural organisation of the light harvesting antenna systems [58,59]. The orphan phylogenetic position of RedCAPs together with an expression pattern similar to LHCF2 transcripts promote this group as an interesting candidate to explain these differences.…”