Examining prestructured β-actin peptides as substrates of histidine methyltransferase SETD3.

The N-His73 methylation of β-actin by histidine methyltransferase SETD3 is required for the integrity of the cellular cytoskeleton. Modulation of SETD3 activity in human cells facilitates cancer-like changes to the cell phenotype. SETD3 binds β-actin in an extended conformation, with a conserved bend-like motif surrounding His73.

Mechanisms of temperature acclimatisation in the psychrotolerant green alga Coccomyxa subellipsoidea C-169 (Trebouxiophyceae).

Despite the interest in different temperature acclimatisations of higher plants, few studies have considered the mechanisms that allow psychrotolerant microalgae to live in a cold environment. Although the analysis of the genomes of some algae revealed the presence of specific genes that encode enzymes that can be involved in the response to stress, this area has not been explored deeply. This work aims to clarify the acclimatisation mechanisms that enable the psychrotolerant green alga Coccomyxa subellipsoidea C-169 to grow in a broad temperature spectrum.

How Light Modulates the Growth of Cells by Changing the Function of Phycobilisomes.

The aim of this study was to examine how light intensity and quality affect the photosynthetic apparatus of cells by modulating the structure and function of phycobilisomes. Cells were grown in equal amounts of white, blue, red, and yellow light of low (LL) and high (HL) intensity. Biochemical characterization, fluorescence emission, and oxygen exchange were used to investigate selected cellular physiological parameters.

How Light Reactions of Photosynthesis in C4 Plants Are Optimized and Protected under High Light Conditions.

Most C4 plants that naturally occur in tropical or subtropical climates, in high light environments, had to evolve a series of adaptations of photosynthesis that allowed them to grow under these conditions. In this review, we summarize mechanisms that ensure the balancing of energy distribution, counteract photoinhibition, and allow the dissipation of excess light energy. They secure effective electron transport in light reactions of photosynthesis, which will lead to the production of NADPH and ATP.

The effect of temperature conditions during growth on the transformation frequency of obtained by electroporation.

In this study, we have shown that transformation efficiency of C-169 obtained by electroporation can be significantly increased by either supra- or sub-optimal growth temperatures.

Stable transformation of unicellular green alga Coccomyxa subellipsoidea C-169 via electroporation.

In this study, we have shown the applicability of electroporation and hygromycin B as a convenient selectable marker for stable nuclear transformation of Coccomyxa subellipsoidea C-169. Since it is the first sequenced eukaryotic microorganism from polar environment, this offers unique opportunities to study adaptation mechanisms to cold.

PEG-mediated, Stable, Nuclear and Chloroplast Transformation of .

The ability to achieve nuclear or chloroplast transformation in plants has been a long standing goal, especially in microalgae research. Over past years there has been only little success, but transient and stable nuclear transformation has been achieved in multiple species. Our newly developed method allows for relatively simple transformation of in both nuclear and chloroplast genome by means of homologous recombination between the genome and a transformation vector.

Deletion of psbQ' gene in Cyanidioschyzon merolae reveals the function of extrinsic PsbQ' in PSII.

We have successfully produced single-cell colonies of C. merolae mutants, lacking the PsbQ' subunit in its PSII complex by application of DTA-aided mutant selection. We have investigated the physiological changes in PSII function and structure and proposed a tentative explanation of the function of PsbQ' subunit in the PSII complex.

Differences in photosynthetic responses of NADP-ME type C4 species to high light.

Three species chosen as representatives of NADP-ME C4 subtype exhibit different sensitivity toward photoinhibition, and great photochemical differences were found to exist between the species. These characteristics might be due to the imbalance in the excitation energy between the photosystems present in M and BS cells, and also due to that between species caused by the penetration of light inside the leaves. Such regulation in the distribution of light intensity between M and BS cells shows that co-operation between both the metabolic systems determines effective photosynthesis and reduces the harmful effects of high light on the degradation of PSII through the production of reactive oxygen species (ROS).

Transformation of the Cyanidioschyzon merolae chloroplast genome: prospects for understanding chloroplast function in extreme environments.

We have successfully transformed an exthemophilic red alga with the chloramphenicol acetyltransferase gene, rendering this organism insensitive to its toxicity. Our work paves the way to further work with this new modelorganism. Here we report the first successful attempt to achieve a stable, under selectable pressure, chloroplast transformation in Cyanidioschizon merolae-an extremophilic red alga of increasing importance as a new model organism.

Chloramphenicol acetyltransferase-a new selectable marker in stable nuclear transformation of the red alga Cyanidioschyzon merolae.

In this study, we have shown the applicability of chloramphenicol acetyltransferase as a new and convenient selectable marker for stable nuclear transformation as well as potential chloroplast transformation of Cyanidioschyzon merolae-a new model organism, which offers unique opportunities for studding the mitochondrial and plastid physiology as well as various evolutionary, structural, and functional features of the photosynthetic apparatus.

The short-term response of Arabidopsis thaliana (C3) and Zea mays (C4) chloroplasts to red and far red light.

Light quality has various effects on photochemistry and protein phosphorylation in Zea mays and Arabidopsis thaliana thylakoids due to different degrees of light penetration across leaves and redox status in chloroplasts. The effect of the spectral quality of light (red, R and far red, FR) on the function of thylakoid proteins in Zea mays and Arabidopsis thaliana was investigated. It was concluded that red light stimulates PSII activity in A.

Lead induced changes in phosphorylation of PSII proteins in low light grown pea plants.

Light-intensity and redox-state induced thylakoid proteins phosphorylation involved in structural changes and in regulation of protein turnover. The presence of heavy metal ions triggers a wide range of cellular responses including changes in plant growth and photosynthesis. Plants have evolved a number of mechanisms to protect photosynthetic apparatus.

Metabolic responses to lead of metallicolous and nonmetallicolous populations of Armeria maritima.

Metabolic responses to Pb(NO₃)₂ (Pb) ions of excised leaves of metallicolous (MPs) and nonmetallicolous populations (NMPs) of Armeria maritima, cultivated on normal soil, were examined. Detached leaves were exposure to Pb for 24 h, and metabolic parameters were investigated. Pb decreased the photosynthesis (Pn) rate and photosystem II (PSII) activity, whereas the photochemical efficiency of PSII remained unchanged.

Light intensity and quality stimulated Deg1-dependent cleavage of PSII components in the chloroplasts of maize.

Recent studies have revealed that photo damages inducing high white light illumination of C3-type plant Arabidopsis thaliana promotes Deg1-mediated degradation of not only photosystem II core proteins D1/D2 but also minor LHCII proteins CP26, CP29 and PSII-associated PsbS protein. Using biochemical and immunological approaches we show that that the substrate pool of the heterologously expressed Deg1 ortholog protease from C4-type plant Zea mays is very similar to that of the A. thaliana in both mesophyll and bundle sheath chloroplasts.

[C4 type photosynthesis].

C4 photosynthesis includes several anatomical and biochemical modifications that allow plants to concentrate CO2 at the site of Rubisco. The photorespiratory pathway is repressed in C4 plants, since the rates of photosynthesis and biomass production are increased. This is an adaptation to high light intensities, high temperatures and dryness.

A pleiotropic drug resistance transporter in Nicotiana tabacum is involved in defense against the herbivore Manduca sexta.

Pleiotropic drug resistance (PDR) transporters are a group of membrane proteins belonging to the ABCG sub-family of ATP binding cassette (ABC) transporters. There is clear evidence for the involvement of plant ABC transporters in resistance to fungal and bacterial pathogens, but not in the biotic stress response to insect or herbivore attack. Here, we describe a PDR transporter, ABCG5/PDR5, from Nicotiana tabacum.

Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 show increased susceptibility to a group of fungal and oomycete pathogens.

SUMMARY The behaviour of Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 was investigated in response to fungal and oomycete infections. The importance of NpPDR1 in plant defence was demonstrated for two organs in which NpPDR1 is constitutively expressed: the roots and the petal epidermis. The roots of the plantlets of two lines silenced for NpPDR1 expression were clearly more sensitive than those of controls to the fungal pathogens Botrytis cinerea, Fusarium oxysporum sp.

Differential turnover of the photosystem II reaction centre D1 protein in mesophyll and bundle sheath chloroplasts of maize.

Photoinhibition is caused by an imbalance between the rates of the damage and repair cycle of photosystem II D1 protein in thylakoid membranes. The PSII repair processes include (i) disassembly of damaged PSII-LHCII supercomplexes and PSII core dimers into monomers, (ii) migration of the PSII monomers to the stroma regions of thylakoid membranes, (iii) dephosphorylation of the CP43, D1 and D2 subunits, (iv) degradation of damaged D1 protein, and (v) co-translational insertion of the newly synthesized D1 polypeptide and reassembly of functional PSII complex. Here, we studied the D1 turnover cycle in maize mesophyll and bundle sheath chloroplasts using a protein synthesis inhibitor, lincomycin.

Structural organization of photosynthetic apparatus in agranal chloroplasts of maize.

We investigated the organization of photosystem II (PSII) in agranal bundle sheath thylakoids from a C(4) plant maize. Using blue native/SDS-PAGE and single particle analysis, we show for the first time that PSII in the bundle sheath (BS) chloroplasts exists in a dimeric form and forms light-harvesting complex II (LHCII).PSII supercomplexes.

High light induced accumulation of two isoforms of the CF1 alpha-subunit in mesophyll and bundle sheath chloroplasts of C4 plants.

The effect of light irradiance on the amount of ATP synthase alpha-subunit in mesophyll (M) and bundle sheath (BS) chloroplasts of C(4) species such as maize (Zea mays L., type NADP-ME), millet (Panicum miliaceum, type NAD-ME) and guinea grass (Panicum maximum, type PEP-CK) was investigated in plants grown under high, moderate and low light intensities equal to 800, 350 and 50 micromol photons m(-2) s(-1), respectively. The results demonstrate that alpha-subunit of ATP synthase in both M and BS chloroplasts is altered by light intensity, but differently in the investigated species.

Comparative analysis of biochemical properties of mesophyll and bundle sheath chloroplasts from various subtypes of C4 plants grown at moderate irradiance.

The photochemical characteristics of mesophyll and bundle sheath chloroplasts isolated from the leaves of C4 species were investigated in Zea mays (NADP-ME type), Panicum miliaceum (NAD-ME type) and Panicum maximum (PEP-CK type) plants. The aim of this work was to gain information about selected photochemical properties of mesophyll and bundle sheath chloroplasts isolated from C4 plants grown in the same moderate light conditions. Enzymatic as well as mechanical methods were applied for the isolation of bundle sheath chloroplasts.

Acclimation of mesophyll and bundle sheath chloroplasts of maize to different irradiances during growth.

The regulation by light of the photosynthetic apparatus, and composition of light-harvesting complexes in mesophyll and bundle sheath chloroplasts was investigated in maize. Leaf chlorophyll content, level of plastoquinone, PSI and PSII activities and Lhc polypeptide compositions were determined in plants grown under high, moderate and low irradiances. Photochemical efficiency of PSII, photochemical fluorescence quenching and non-photochemical fluorescence quenching over a range of actinic irradiances were also determined, using chlorophyll a fluorescence analysis.

Organization and activity of photosystems in the mesophyll and bundle sheath chloroplasts of maize.

Photosystem I and Photosystem II activities, as well as polypeptide content of chlorophyll (Chl)-protein complexes were analyzed in mesophyll (M) and bundle sheath (BS) chloroplasts of maize (Zea mays L.) growing under moderate and very low irradiance. This paper discusses the application of two techniques: mechanical and enzymatic, for separation of M and BS chloroplasts.