Spectral Properties of Long-Wavelength Chlorophylls in Barley Photosystem I Depend on Intimate Interaction Between LHCA1, LHCA4 and the Reaction Centre

The attachment of long wavelength absorbing π-conjugated chromophores to poly(methyl-phenylsilylene) (PMPSi) via reactions of its formylated derivative is described. Some of the obtained polymers exhibit improved photostability in comparison with the parent polymer. Their spectral properties and photoconductivity are discussed. Ultrathin layers and multilayers were prepared from polar derivatives of PMPSi by the Langmuir-Blodgett technique and their photoconductive behaviour was studied.

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The Effect of Some Inhibitors of Photosynthetic Electron Transport on the Kinetics of Redox Changes of the Reaction Centre Chlorophyll of Photosystem I (P700) and of Cytochrome f at Sub-Zero Temperatures

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1979.tb06273.x ◽

1979 ◽

Vol 102 (1) ◽

pp. 139-145 ◽

Cited By ~ 9

Author(s):

Lars F. OLSEN ◽

Raymond P. COX

Keyword(s):

Electron Transport ◽

Photosystem I ◽

Photosynthetic Electron Transport ◽

Cytochrome F ◽

Reaction Centre ◽

Kinetics Of

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Early Archean origin of heterodimeric Photosystem I

10.1101/225888 ◽

2017 ◽

Author(s):

Tanai Cardona

Keyword(s):

Gene Duplication ◽

Photosystem I ◽

Water Oxidation ◽

Duplication Event ◽

Oxygenic Photosynthesis ◽

Recent Common Ancestor ◽

Type I ◽

Reaction Centre ◽

Gene Duplication Event ◽

Most Recent Common Ancestor

AbstractWhen and how oxygenic photosynthesis originated remains controversial. Wide uncertainties exist for the earliest detection of biogenic oxygen in the geochemical record or the origin of water oxidation in ancestral lineages of the phylum Cyanobacteria. A unique trait of oxygenic photosynthesis is that the process uses a Type I reaction centre with a heterodimeric core, also known as Photosystem I, made of two distinct but homologous subunits, PsaA and PsaB. In contrast, all other known Type I reaction centres in anoxygenic phototrophs have a homodimeric core. A compelling hypothesis for the evolution of a heterodimeric Type I reaction centre is that the gene duplication that allowed the divergence of PsaA and PsaB was an adaptation to incorporate photoprotective mechanisms against the formation of reactive oxygen species, therefore occurring after the origin of water oxidation to oxygen. Here I show, using sequence comparisons and Bayesian relaxed molecular clocks that this gene duplication event may have occurred in the early Archean more than 3.4 billion years ago, long before the most recent common ancestor of crown group Cyanobacteria and the Great Oxidation Event. If the origin of water oxidation predated this gene duplication event, then that would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life.

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