scholarly journals The structure of Photosystem I acclimated to far-red light illuminates an ecologically important acclimation process in photosynthesis

2020 ◽  
Vol 6 (6) ◽  
pp. eaay6415 ◽  
Author(s):  
Christopher Gisriel ◽  
Gaozhong Shen ◽  
Vasily Kurashov ◽  
Ming-Yang Ho ◽  
Shangji Zhang ◽  
...  
Keyword(s):  
Photosystem I ◽  
Binding Sites ◽  
Structural Changes ◽  
Red Light ◽  
Oxygenic Photosynthesis ◽  
Cryo Electron Microscopy ◽  
Photosynthetic Proteins ◽  
Functional Differences ◽  
Light Utilization ◽  
Chlorophyll F

Phototrophic organisms are superbly adapted to different light environments but often must acclimate to challenging competition for visible light wavelengths in their niches. Some cyanobacteria overcome this challenge by expressing paralogous photosynthetic proteins and by synthesizing and incorporating ~8% chlorophyll f into their Photosystem I (PSI) complexes, enabling them to grow under far-red light (FRL). We solved the structure of FRL-acclimated PSI from the cyanobacterium Fischerella thermalis PCC 7521 by single-particle, cryo–electron microscopy to understand its structural and functional differences. Four binding sites occupied by chlorophyll f are proposed. Subtle structural changes enable FRL-adapted PSI to extend light utilization for oxygenic photosynthesis to nearly 800 nm. This structure provides a platform for understanding FRL-driven photosynthesis and illustrates the robustness of adaptive and acclimation mechanisms in nature.

scholarly journals Structure of the far-red light utilizing photosystem I of Acaryochloris

2020 ◽  
Author(s):  
Tasuku Hamaguchi ◽  
Keisuke Kawakami ◽  
Kyoko Shinzawa-Itoh ◽  
Natsuko Inoue-Kashino ◽  
Shigeru Itoh ◽  
...  
Keyword(s):  
Photosystem I ◽  
Red Light ◽  
Primary Electron ◽  
Oxygenic Photosynthesis ◽  
Energy Yield ◽  
Type I ◽  
Cryo Electron Microscopy ◽  
Primary Electron Acceptor ◽  
Acaryochloris Marina ◽  
Electron Carriers

Abstract Acaryochloris marina is a cyanobacterium that can, uniquely, use far-red light for oxygenic photosynthesis. Here, we report the structure of the photosystem I reaction center of A. marina determined by cryo-electron microscopy at 2.5 Å resolution. The structure reveals a unique arrangement of electron carriers and light harvesting pigments. The primary electron donor P740 is a dimer of chlorophyll d/d′ and the primary electron acceptor pheophytin a, a metal-less chlorin different from the chlorophyll a common to all other oxygenic type I reaction centers. The architecture of the 11 subunits and identity of key components help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.

scholarly journals Novel chlorophylls and new directions in photosynthesis research

2015 ◽  
Vol 42 (6) ◽  
pp. 493 ◽  
Author(s):  
Yaqiong Li ◽  
Min Chen
Keyword(s):  
Chlorophyll A ◽  
Red Light ◽  
Oxygenic Photosynthesis ◽  
Ecological Niches ◽  
Absorption Bands ◽  
Absorption Region ◽  
Chlorophyll D ◽  
And Function ◽  
Unique Status ◽  
Chlorophyll F

Chlorophyll d and chlorophyll f are red-shifted chlorophylls, because their Qy absorption bands are significantly red-shifted compared with chlorophyll a. The red-shifted chlorophylls broaden the light absorption region further into far red light. The presence of red-shifted chlorophylls in photosynthetic systems has opened up new possibilities of research on photosystem energetics and challenged the unique status of chlorophyll a in oxygenic photosynthesis. In this review, we report on the chemistry and function of red-shifted chlorophylls in photosynthesis and summarise the unique adaptations that have allowed the proliferation of chlorophyll d- and chlorophyll f-containing organisms in diverse ecological niches around the world.

Photochemistry beyond the red limit in chlorophyll f–containing photosystems

Science ◽  
2018 ◽  
Vol 360 (6394) ◽  
pp. 1210-1213 ◽  
Author(s):  
Dennis J. Nürnberg ◽  
Jennifer Morton ◽  
Stefano Santabarbara ◽  
Alison Telfer ◽  
Pierre Joliot ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Charge Separation ◽  
Red Light ◽  
Oxygenic Photosynthesis ◽  
Long Wavelength ◽  
Photosystems I And Ii ◽  
Biophysical Studies ◽  
A Charge ◽  
Photosystem I And Ii ◽  
Chlorophyll F

Photosystems I and II convert solar energy into the chemical energy that powers life. Chlorophyll a photochemistry, using red light (680 to 700 nm), is near universal and is considered to define the energy “red limit” of oxygenic photosynthesis. We present biophysical studies on the photosystems from a cyanobacterium grown in far-red light (750 nm). The few long-wavelength chlorophylls present are well resolved from each other and from the majority pigment, chlorophyll a. Charge separation in photosystem I and II uses chlorophyll f at 745 nm and chlorophyll f (or d) at 727 nm, respectively. Each photosystem has a few even longer-wavelength chlorophylls f that collect light and pass excitation energy uphill to the photochemically active pigments. These photosystems function beyond the red limit using far-red pigments in only a few key positions.

Femtosecond infrared spectroscopy of chlorophyll f-containing photosystem I

2019 ◽  
Vol 21 (3) ◽  
pp. 1224-1234 ◽  
Author(s):  
Noura Zamzam ◽  
Marius Kaucikas ◽  
Dennis J. Nürnberg ◽  
A. William Rutherford ◽  
Jasper J. van Thor
Keyword(s):  
Infrared Spectroscopy ◽  
Photosystem I ◽  
Charge Separation ◽  
Light Harvesting ◽  
Red Light ◽  
Time Resolved ◽  
Time Resolved Infrared Spectroscopy ◽  
Chlorophyll F

Femtosecond time resolved infrared spectroscopy of far-red light grown photosystem I shows chlorophyll f contributions in light harvesting and charge separation.

scholarly journals Harvesting far-red light: Functional integration of chlorophyll f into Photosystem I complexes of Synechococcus sp. PCC 7002

2020 ◽  
Vol 1861 (8) ◽  
pp. 148206 ◽  
Author(s):  
Martijn Tros ◽  
Luca Bersanini ◽  
Gaozhong Shen ◽  
Ming-Yang Ho ◽  
Ivo H.M. van Stokkum ◽  
...  
Keyword(s):  
Photosystem I ◽  
Functional Integration ◽  
Red Light ◽  
Synechococcus Sp ◽  
Chlorophyll F

scholarly journals Evidence that chlorophyll f functions solely as an antenna pigment in far-red-light photosystem I from Fischerella thermalis PCC 7521

2020 ◽  
Vol 1861 (5-6) ◽  
pp. 148184 ◽  
Author(s):  
Dmitry A. Cherepanov ◽  
Ivan V. Shelaev ◽  
Fedor E. Gostev ◽  
Arseniy V. Aybush ◽  
Mahir D. Mamedov ◽  
...  
Keyword(s):  
Photosystem I ◽  
Red Light ◽  
Antenna Pigment ◽  
Chlorophyll F

scholarly journals Structure of the far-red light utilizing photosystem I of Acaryochloris marina

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tasuku Hamaguchi ◽  
Keisuke Kawakami ◽  
Kyoko Shinzawa-Itoh ◽  
Natsuko Inoue-Kashino ◽  
Shigeru Itoh ◽  
...  
Keyword(s):  
Reaction Center ◽  
Photosystem I ◽  
Red Light ◽  
Primary Electron ◽  
Photochemical Reactions ◽  
Oxygenic Photosynthesis ◽  
Energy Yield ◽  
Type I ◽  
Cyanobacterial Species ◽  
Acaryochloris Marina

AbstractAcaryochloris marina is one of the cyanobacterial species that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of A. marina photosystem I (PSI) reaction center, determined by cryo-electron microscopy at 2.58 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments distinct from other type I reaction centers. The paired chlorophyll, or special pair (also referred to as P740 in this case), is a dimer of chlorophyll d and its epimer chlorophyll d′. The primary electron acceptor is pheophytin a, a metal-less chlorin. We show the architecture of this PSI reaction center is composed of 11 subunits and we identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.

scholarly journals Structure of the far-red light utilizing photosystem I of Acaryochloris marina

2021 ◽  
Author(s):  
Tasuku Hamaguchi ◽  
Keisuke Kawakami ◽  
Kyoko Shinzawa-Itoh ◽  
Natsuko Inoue-Kashino ◽  
Shigeru Itoh ◽  
...  
Keyword(s):  
Reaction Center ◽  
Photosystem I ◽  
Red Light ◽  
Primary Electron ◽  
Photochemical Reactions ◽  
Reaction Centers ◽  
Oxygenic Photosynthesis ◽  
Energy Yield ◽  
Type I ◽  
Acaryochloris Marina

Abstract Acaryochloris marina is one of the cyanobacteria that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of the photosystem I reaction center of A. marina determined by cryo-electron microscopy at 2.5 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments different from other type I reaction centers. The paired chlorophyll, so-called special pair, of P740 is a dimer of chlorophyll d/d′ and the primary electron acceptor is pheophytin a, a metal-less chlorin different from the chlorophyll a common to all other type I reaction centers. Here we show the architecture of the photosystem I reaction center is composed of 11 subunits and identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.

Cryo-electron microscopy of two-dimensional crystals of reduced type B botulinum neurotoxin

1992 ◽  
Vol 50 (1) ◽  
pp. 530-531
Author(s):  
P. F. Flicker ◽  
V.S. Kulkarni ◽  
J. P. Robinson ◽  
G. Stubbs ◽  
B. R. DasGupta
Keyword(s):  
Disulfide Bonds ◽  
Clostridium Botulinum ◽  
Structural Changes ◽  
Two Dimensional ◽  
Type B ◽  
Single Chain ◽  
Muscle Paralysis ◽  
Cryo Electron Microscopy ◽  
Disulfide Linkages ◽  
Intracellular Action

Botulinum toxin is a potent neurotoxin produced by Clostridium botulinum. The toxin inhibits release of neurotransmitter, causing muscle paralysis. There are several serotypes, A to G, all of molecular weight about 150,000. The protein exists as a single chain or or as two chains, with two disulfide linkages. In a recent investigation on intracellular action of neurotoxins it was reported that type B neurotoxin can inhibit the release of Ca++-activated [3H] norepinephrine only if the disulfide bonds are reduced. In order to investigate possible structural changes in the toxin upon reduction of the disulfide bonds, we have prepared two-dimensional crystals of reduced type B neurotoxin. These two-dimensional crystals will be compared with those of the native (unreduced) type B toxin.

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