scholarly journals Role of an ancient light-harvesting protein of PSI in light absorption and photoprotection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yandu Lu ◽  
Qinhua Gan ◽  
Masakazu Iwai ◽  
Alessandro Alboresi ◽  
Adrien Burlacot ◽  
...  
Keyword(s):  
Light Absorption ◽  
Red Algae ◽  
Light Harvesting ◽  
High Light ◽  
Secondary Endosymbiosis ◽  
Ros Production ◽  
Nannochloropsis Oceanica ◽  
Wild Type ◽  
Dynamic Balancing

AbstractDiverse algae of the red lineage possess chlorophyll a-binding proteins termed LHCR, comprising the PSI light-harvesting system, which represent an ancient antenna form that evolved in red algae and was acquired through secondary endosymbiosis. However, the function and regulation of LHCR complexes remain obscure. Here we describe isolation of a Nannochloropsis oceanica LHCR mutant, named hlr1, which exhibits a greater tolerance to high-light (HL) stress compared to the wild type. We show that increased tolerance to HL of the mutant can be attributed to alterations in PSI, making it less prone to ROS production, thereby limiting oxidative damage and favoring growth in HL. HLR1 deficiency attenuates PSI light-harvesting capacity and growth of the mutant under light-limiting conditions. We conclude that HLR1, a member of a conserved and broadly distributed clade of LHCR proteins, plays a pivotal role in a dynamic balancing act between photoprotection and efficient light harvesting for photosynthesis.

scholarly journals Involvement of Lhcb6 and Lhcb5 in Photosynthesis Regulation in Physcomitrella patens Response to Abiotic Stress

2019 ◽  
Vol 20 (15) ◽  
pp. 3665 ◽  
Author(s):  
Xingji Peng ◽  
Xingguang Deng ◽  
Xiaoya Tang ◽  
Tinghong Tan ◽  
Dawei Zhang ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Physcomitrella Patens ◽  
Light Harvesting ◽  
Light Stress ◽  
High Light ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Knock Out ◽  
Non Photochemical Quenching ◽  
Photosynthesis Regulation

There are a number of highly conserved photosystem II light-harvesting antenna proteins in moss whose functions are unclear. Here, we investigated the involvement of chlorophyll-binding proteins, Lhcb6 and Lhcb5, in light-harvesting and photosynthesis regulation in Physcomitrella patens. Lhcb6 or Lhcb5 knock-out resulted in a disordered thylakoid arrangement, a decrease in the number of grana membranes, and an increase in the number of starch granule. The absence of Lhcb6 or Lhcb5 did not noticeably alter the electron transport rates. However, the non-photochemical quenching activity in the lhcb5 mutant was dramatically reduced when compared to wild-type or lhcb6 plants under abiotic stress. Lhcb5 plants were more sensitive to photo-inhibition, while lhcb6 plants showed little difference compared to the wild-type plants under high-light stress. Moreover, both mutants showed a growth malformation phenotype with reduced chlorophyll content in the gametophyte. These results suggested that Lhcb6 or Lhcb5 played a unique role in plant development, thylakoid organization, and photoprotection of PSII in Physcomitrella, especially when exposed to high light or osmotic environments.

scholarly journals β-Naphthoflavone-Induced Mitochondrial Respiratory Damage in Cyp1 Knockout Mouse and in Cell Culture Systems: Attenuation by Resveratrol Treatment

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Suresh Kumar Anandasadagopan ◽  
Naveen M. Singh ◽  
Haider Raza ◽  
Seema Bansal ◽  
Venkatesh Selvaraj ◽  
...  
Keyword(s):  
Mitochondrial Gene ◽  
Ros Production ◽  
Wild Type ◽  
Double Knockout ◽  
Respiratory Dysfunction ◽  
Mitochondrial Ros ◽  
Cell Culture Systems ◽  
Mitochondrial Defects

A number of xenobiotic-inducible cytochrome P450s (CYPs) are now known to be localized in the mitochondrial compartment, though their pharmacological or toxicological roles remain unclear. Here, we show that BNF treatment markedly inhibits liver mitochondrial O2 consumption rate (OCR), ADP-dependent OCR, and also reserve OCR, in wild-type mice but not in Cyp1a1/1a2(−/−) double knockout mice. BNF treatment markedly affected mitochondrial complex I and complex IV activities and also attenuated mitochondrial gene expression. Furthermore, under in vitro conditions, BNF treatment induced cellular ROS production, which was inhibited by mitochondria-targeted antioxidant Mito-CP and CYP inhibitor proadefin, suggesting that most of the ROS production was intramitochondrial and probably involved the catalytic activity of mitochondrial CYP1 enzymes. Interestingly, our results also show that the AHR antagonist resveratrol, markedly attenuated BNF-induced liver mitochondrial defects in wild-type mice, confirming the role of AHR and AHR-regulated CYP1 genes in eliciting mitochondrial dysfunction. These results are consistent with reduced BNF-induced mitochondrial toxicity in Cyp1a1/1a2(−/−) mice and elevated ROS production in COS cells stably expressing CYP1A1. We propose that increased mitochondrial ROS production and respiratory dysfunction are part of xenobiotic toxicity. Resveratrol, a chemopreventive agent, renders protection against BNF-induced toxicity.

The Role of Aromatic Phenylalanine Residues in Binding Carotenoid to Light-Harvesting Model and Wild-Type Complexes

2008 ◽  
Vol 382 (1) ◽  
pp. 154-166 ◽  
Author(s):  
A. García-Martín ◽  
A. Pazur ◽  
B. Wilhelm ◽  
M. Silber ◽  
B. Robert ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Wild Type

scholarly journals What Happened to the Phycobilisome?

Biomolecules ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 748 ◽  
Author(s):  
Beverley R. Green
Keyword(s):  
Green Algae ◽  
Red Algae ◽  
Light Harvesting ◽  
Antenna System ◽  
Reaction Centers ◽  
Photosynthetic Reaction Centers ◽  
Photosynthetic Eukaryote ◽  
Light Harvesting Complex ◽  
Major Loss

The phycobilisome (PBS) is the major light-harvesting complex of photosynthesis in cyanobacteria, red algae, and glaucophyte algae. In spite of the fact that it is very well structured to absorb light and transfer it efficiently to photosynthetic reaction centers, it has been completely lost in the green algae and plants. It is difficult to see how selection alone could account for such a major loss. An alternative scenario takes into account the role of chance, enabled by (contingent on) the evolution of an alternative antenna system early in the diversification of the three lineages from the first photosynthetic eukaryote.

scholarly journals Reciprocity between retrograde signal and putative metalloprotease reconfigures plastidial metabolism and structure

2021 ◽  
Author(s):  
Jin-Zheng Wang ◽  
Wilhelmina van de Ven ◽  
Yanmei Xiao ◽  
Xiang He ◽  
Haiyan Ke ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Light Treatment ◽  
High Light ◽  
Retrograde Signaling ◽  
Zinc Binding ◽  
Adaptive Responses ◽  
Wild Type ◽  
Cellular Integrity ◽  
Retrograde Signal

Reconfiguration of the plastidial proteome in response to environmental inputs is central to readjustment of its metabolic and structural states. This is necessary for the functionality of this metabolic hub, and the maintenance of organismal integrity. This report establishes the role of the plastidial retrograde signaling metabolite, MEcPP, in increasing the abundance of the putative plastidial metalloprotease (VIR3), and the ensuing decline of VIR3 target enzymes, ascorbate peroxidase and glyceraldehyde 3-phophate dehydrogenase B. The decreased abundance of these enzymes is linked to increased levels of their substrates: H2O2, an elicitor of salicylic acid production and stromule formation; and G3P the substrate for MEcPP synthesis. High-light treatment of wild type plants recapitulated the VIR3-associated reconfiguration of the plastidial metabolic and structural states. These results identify a previously unrecognized link between the stress-induced plastidial retrograde signaling metabolite and a putative zinc-binding metalloprotease. Moreover, the data reveal that the reciprocity between these two components, results in the reconfiguration of the metabolic and structural states of the plastid, deemed necessary to maintain cellular integrity and to shape adaptive responses.

Differential Role of Components of the Fibrinolytic System in the Formation and Removal of Thrombus Induced by Endothelial Injury

1999 ◽  
Vol 81 (04) ◽  
pp. 601-604 ◽  
Author(s):  
Hiroyuki Matsuno ◽  
Osamu Kozawa ◽  
Masayuki Niwa ◽  
Shigeru Ueshima ◽  
Osamu Matsuo ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Thrombus Formation ◽  
Endothelial Injury ◽  
Fibrinolytic System ◽  
Tissue Type ◽  
Clot Lysis ◽  
Wild Type ◽  
Type Plasminogen Activator ◽  
Pai 1

SummaryThe role of fibrinolytic system components in thrombus formation and removal in vivo was investigated in groups of six mice deficient in urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), or plasminogen activator inhibitor-1 (PAI-1) (u-PA-/-, t-PA-/- or PAI-1-/-, respectively) or of their wild type controls (u-PA+/+, t-PA+/+ or PAI-1+/+). Thrombus was induced in the murine carotid artery by endothelial injury using the photochemical reaction between rose bengal and green light (540 nm). Blood flow was continuously monitored for 90 min on day 0 and for 20 min on days 1, 2 and 3. The times to occlusion after the initiation of endothelial injury in u-PA+/+, t-PA+/+ or PAI-1+/+ mice were 9.4 ± 1.3, 9.8 ± 1.1 or 9.7 ± 1.6 min, respectively. u-PA-/- and t-PA-/- mice were indistinguishable from controls, whereas that of PAI-1-/- mice were significantly prolonged (18.4 ± 3.7 min). Occlusion persisted for the initial 90 min observation period in 10 of 18 wild type mice and was followed by cyclic reflow and reocclusion in the remaining 8 mice. At day 1, persistent occlusion was observed in 1 wild type mouse, 8 mice had cyclic reflow and reocclusion and 9 mice had persistent reflow. At day 2, all injured arteries had persistent reflow. Persistent occlusion for 90 min on day 0 was observed in 3 u-PA-/-, in all t-PA-/- mice at day 1 and in 2 of the t-PA-/-mice at day 2 (p <0.01 versus wild type mice). Persistent patency was observed in all PAI-1-/- mice at day 1 and in 5 of the 6 u-PA-/- mice at day 2 (both p <0.05 versus wild type mice). In conclusion, t-PA increases the rate of clot lysis after endothelial injury, PAI-1 reduces the time to occlusion and delays clot lysis, whereas u-PA has little effect on thrombus formation and spontaneous lysis.

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