Modulation of PSI and PSII Organization During Loss and Repair of Photosynthetic Activity in a Temperature Sensitive Mutant  of <i>Chlorella pyrenoidosa</i>

Lavintman, Nelly; Galling, Gottfried; Ohad, Itzhak

doi:10.1104/pp.68.6.1264

Cited by 7 publications

(2 citation statements)

References 15 publications

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“…These experiments demonstrate that not only the few Chl molecules required for the assembly of RCII, but also the large amount of Chl required for the assembly of the PS II core antenna, CP43 and CP 47, as well as for the formation of PS I, could be taken from pre-existing Chl proteins (Gershoni et al, 1982). Chlorophyll transfer from pre-existing antenna complexes to newly formed reaction centers was also reported in Chlorella pyrenoidosa cells (Lavintman et al, 1981) and vascular plants (Dannehl et al, 1996).…”

Section: The Role Of Chlorophyll a And -Carotene In The Reassembly Of Ps IIsupporting

confidence: 52%

State Transition and Photoinhibition

Keren

Ohad

The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas

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protein. Excessive excitation induces a stepwise inactivation of PS II, affecting primarily its acceptor side components, thereby promoting charge recombination and oxidative damage. Infrequent excitation of PS II ('low light'), promotes charge recombination driven by the equilibrium between the oxidized states of the PS II donor side manganese cluster and the reduced semiquinone acceptorIn this process are regenerated and their recombination results in oxidative damage exposing the PS II proteins to proteolytic cleavage. De novo protein synthesis and reassembly of PS II compensate for photoinactivation and degradation of the D1 protein. This process involves dissociation of the residual PS II core proteins from the antenna complex, lateral migration from the appressed to the non-appressed lamellae and reassembly with precursor pD1 protein, newly synthesized by polyribosomes bound to non-appressed lamellae. Processing of pD1, light dependent reactivation of the donor side Mn cluster, lateral migration of the reactivated PS II core to the appressed lamellae, and its reassociation with LHCII regenerates active PS II units and complete the PS II photoinactivation and repair cycle. Thus, photoinactivation and repair of PS II activity are regulated at the metabolic and molecular levels and are modulated by environmental changes.

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Section: The Role Of Chlorophyll a And -Carotene In The Reassembly Of Ps IIsupporting

confidence: 52%

State Transition and Photoinhibition

Keren

Ohad

The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas

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“…In order to differentiate between the direct and indirect effects of a mutation, a conditional expression of the phenotype comes in very handy. Several studies reported the isolation of mutants with temperature-sensitive photosynthesis ( Weaver, 1971 ; Sherman and Cunningham, 1977 ; Lavintman et al, 1981 ; Spreitzer et al, 1988 ; Sarma and Singh, 1995 ; Liu et al, 2007 ). These mutants exhibited a defective photosynthetic machinery at high temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature Sensitive Photosynthesis: Point Mutated CEF-G, PRK, or PsbO Act as Temperature-Controlled Switches for Essential Photosynthetic Processes

Bayro-Kaiser

Nelson

2020

Front. Plant Sci.

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Temperature sensitive mutants have been widely used to study structure, biogenesis and function of a large variety of essential proteins. However, this method has not yet been exploited for the study of photosynthesis. We used negative selection to isolate temperature-sensitive-photoautotrophic (TSP) mutants in Chlamydomonas reinhardtii. From a population of randomly mutagenized cells (n=12,000), a significant number of TSP mutants (n=157) were isolated. They were able to grow photoautotrophically at 25°C, but lacked this ability at 37°C. Further phenotypic characterization of these mutants enabled the identification of three unique and highly interesting mutant strains. Following, the selected strains were genetically characterized by extensive crossing and whole genome sequencing. Correspondingly, the single amino acid changes P628F in the Chloroplast-Elongation-Factor-G (CEF-G), P129L in Phosphoribulokinase (PRK), and P101H in an essential subunit of Photosystem II (PsbO) were identified. These key changes alter the proteins in such way that they were functional at the permissive temperature, however, defective at the restrictive temperature. These mutants are presented here as superb and novel tools for the study of a wide range of aspects relevant to photosynthesis research, tackling three distinct and crucial photosynthetic processes: Chloroplast translation, PET-chain, and CBB-cycle.

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