Evolution photosynthetic apparatus

VK Yachandra, RD Guiles, K Sauer and MP Klein (1986) The state of manganese in the photosynthetic apparatus. 5. The chloride effect in photosynthetic oxygen evolution. Is halide coordinated to the EPR-active manganese in O evoiving complex Studies of substructure of the low-temperature multiline EPR signal. Biochim Biophys Acta 850 333-342... 

The PSI complex in thylakoid membranes contains subunits encoded each by the nuclear and chloroplast genomes. A few years ago we initiated research on PSI biogenesis with a special emphasis on the contribution of the nuclear genome. In this article we would like to summarize our recent work briefly, and then discuss the role of the nuclear genome in relation to the evolution of photosynthetic apparatus. The details of our recent work will be described elsewhere. 

Comparative analysis of the PSI subunits among pure line and alloploid species in Nicotiana revealed that an alloploid genome brings about polymorphism of nuclear-encoded subunits (Obokata et al. submitted). This implies that polyploidy and interspecific hybrids have complicated the subunit composition of the photosynthetic apparatus during the plant evolutions. 

Scharf K-D, Berberich T, Ebersberger I, Nover L (2012) The plant heat stress transcription factor (Hsf) family structure, function and evolution. Biochim Biophys Acta 1819 104-119 Seki M, Umezawa T, Urano K, ShinozaM K (2007) Regulatory metabolic networks in drought stress responses. Curr Opin Plant Biol 10 296-302 Sfichi L, loannidis N, Kotzabasis K (2004) Thylakoid-associated polyamines adjust the UV-B sensitivity of the photosynthetic apparatus by means of light-harvesting complex II changes. Photochem Photobiol 80 499-506... 

Before and during stress were collected A(230 p ), A(800 Pi) and electron transport rate, J. J was taken as 02 evolution rate x 4 in 8% C02. We extimate a potential assimilation rate from J and NADPH limitation at pi of 800 ubar by modelling a potential photosynthetic flux as Am =J(Pi-r ) / (4pj +8r ) - Rd, where eventually r and Rd can be evaluated by gas exchange on the same apparatus (6). Within these constraints we can compare Am values scaled to the Am of control and this should give the metabolic effect of the stress. The same comparison between C02 gas exchange actual rates includes diffusional heterogeneity and one can quantitate its relative effect. 

Such a theory of metabolic and photosynthetic evolution goes far towards explaining the similarities and differences amongst the various metabolic processes as we know them today. The path of carbon reduction in photosynthesis employs many reactions which are similar to those employed by heterotrophic organisms in the oxidation of carbohydrates. The apparatus for transporting electrons from water to the point of reduction of carbon dioxide in photosynthesis is similar in many aspects to the apparatus used for the transport of electrons from the oxidation of carbohydrate to oxygen in respiration. 

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