9 results found
Trinugroho JP, Beckova M, Shao S, et al., 2020, Chlorophyll f synthesis by a super-rogue photosystem II complex (vol 6, pg 238, 2020), NATURE PLANTS, Vol: 6, Pages: 427-427, ISSN: 2055-026X
Trinugroho J, Bečková M, Shao S, et al., 2020, Chlorophyll f synthesis by a super-rogue photosystem II complex, Nature Plants, Vol: 6, Pages: 238-244, ISSN: 2055-0278
Certain cyanobacteria synthesize chlorophyll molecules (Chl d and Chl f) that absorb in the far-red region of the solar spectrum, thereby extending the spectral range of photosynthetically active radiation1,2. The synthesis and introduction of these far-red chlorophylls into the photosynthetic apparatus of plants might improve the efficiency of oxygenic photosynthesis, especially in far-red enriched environments, such as in the lower regions of the canopy3. Production of Chl f requires the ChlF subunit, also known as PsbA4 (ref. 4) or super-rogue D1 (ref. 5), a paralogue of the D1 subunit of photosystem II (PSII) which, together with D2, bind cofactors involved in the light-driven oxidation of water. Current ideas suggest that ChlF oxidizes Chl a to Chl f in a homodimeric ChlF reaction centre (RC) complex and represents a missing link in the evolution of the heterodimeric D1/D2 RC of PSII (refs. 4,6). However, unambiguous biochemical support for this proposal is lacking. Here, we show that ChlF can substitute for D1 to form modified PSII complexes capable of producing Chl f. Remarkably, mutation of just two residues in D1 converts oxygen-evolving PSII into a Chl f synthase. Overall, we have identified a new class of PSII complex, which we term ‘super-rogue’ PSII, with an unexpected role in pigment biosynthesis rather than water oxidation.
Zou Z, Shao S, Zou R, et al., 2019, Linking the low-density lipoprotein receptor-binding segment enables the therapeutic 5-YHEDA peptide to cross the blood-brain barrier and scavenge excess iron and radicals in the brain of senescent mice., Alzheimers Dement (N Y), Vol: 5, Pages: 717-731
Introduction: Iron accumulates in the brain during aging, which catalyzes radical formation, causing neuronal impairment, and is thus considered a pathogenic factor in Alzheimer's disease (AD). To scavenge excess iron-catalyzed radicals and thereby protect the brain and decrease the incidence of AD, we synthesized a soluble pro-iron 5-YHEDA peptide. However, the blood-brain barrier (BBB) blocks large drug molecules from entering the brain and thus strongly reduces their therapeutic effects. However, alternative receptor- or transporter-mediated approaches are possible. Methods: A low-density lipoprotein receptor (LDLR)-binding segment of Apolipoprotein B-100 was linked to the 5-YHEDA peptide (bs-5-YHEDA) and intracardially injected into senescent (SN) mice that displayed symptoms of cognitive impairment similar to those of people with AD. Results: We successfully delivered 5-YHEDA across the BBB into the brains of the SN mice via vascular epithelium LDLR-mediated endocytosis. The data showed that excess brain iron and radical-induced neuronal necrosis were reduced after the bs-5-YHEDA treatment, together with cognitive amelioration in the SN mouse, and that the senescence-associated ferritin and transferrin increase, anemia and inflammation reversed without kidney or liver injury. Discussion: bs-5-YHEDA may be a mild and safe iron remover that can cross the BBB and enter the brain to relieve excessive iron- and radical-induced cognitive disorders.
Shao S, Yu J, Nixon PJ, 2019, Selective replacement of the damaged D1 reaction center subunit during the repair of the oxygen-evolving photosystem II complex, Oxygen Production and Reduction in Artificial and Natural Systems, Editors: Barber, Ruban, Nixon, Publisher: World Scientific, Pages: 319-338
The multi-subunit photosystem II (PSII) pigment-protein complex found in plants, algae and cyanobacteria is nature’s biological catalyst for producing oxygen from water. PSII needs sunlight to drive water oxidation but too much light can cause irreversible damage to pigments and proteins within PSII and loss of enzyme activity. Damaged PSII complexes can, however, be repaired in a highly selective process involving the replacement of damaged components by newly synthesized copies and the recycling of undamaged protein subunits and co-factors. Although substantial progress has been made to identify the enzymes and accessory factors involved in repair, many fundamental questions remain unanswered. In this chapter we discuss recent ideas on how the damaged D1 reaction center subunit, which is the subunit most prone to damage in PSII, is specifically recognized for replacement. Detachment of CP43 allowing access by FtsH proteases to the N-terminal tail of D1 seems to underpin selective degradation.
Cardona T, Shao S, Nixon PJ, 2018, Enhancing photosynthesis in plants: the light reactions, Essays in Biochemistry, Vol: 62, Pages: 85-94, ISSN: 0071-1365
In this review, we highlight recent research and current ideas on how to improve the efficiency of the light reactions of photosynthesis in crops. We note that the efficiency of photosynthesis is a balance between how much energy is used for growth and the energy wasted or spent protecting the photosynthetic machinery from photodamage. There are reasons to be optimistic about enhancing photosynthetic efficiency, but many appealing ideas are still on the drawing board. It is envisioned that the crops of the future will be extensively genetically modified to tailor them to specific natural or artificial environmental conditions.
Shao S, Cardona T, Nixon PJ, 2018, Early emergence of the FtsH proteases involved in Photosystem II repair, Photosynthetica, Vol: 56, Pages: 163-177, ISSN: 0300-3604
Efficient degradation of damaged D1 during the repair of PSII is carried out by a set of dedicated FtsH proteases in the thylakoid membrane. Here we investigated whether the evolution of FtsH could hold clues to the origin of oxygenic photosynthesis. A phylogenetic analysis of over 6000 FtsH protease sequences revealed that there are three major groups of FtsH proteases originating from gene duplication events in the last common ancestor of bacteria, and that the FtsH proteases involved in PSII repair make a distinct clade branching out before the divergence of FtsH proteases found in all groups of anoxygenic phototrophic bacteria. Furthermore, we showed that the phylogenetic tree of FtsH proteases in phototrophic bacteria is similar to that for Type I and Type II reaction centre proteins. We conclude that the phylogeny of FtsH proteases is consistent with an early origin of water oxidation chemistry.
Shao S, Cardona T, Nixon PJ, 2018, Erratum to: Early emergence of the FtsH proteases involved in photosystem II repair, Photosynthetica, Pages: 1-2, ISSN: 0300-3604
© 2018 The Institute of Experimental Botany Page 1: The verb ‚make“ was used instead of ‚form“ in the following sentence. Instead of A phylogenetic analysis of over 6000 FtsH protease sequences revealed that there are three major groups of FtsH proteases originating from gene duplication events in the last common ancestor of bacteria, and that the FtsH proteases involved in PSII repair make a distinct clade branching out before the divergence of FtsH proteases found in all groups of anoxygenic phototrophic bacteria. It should read A phylogenetic analysis of over 6000 FtsH protease sequences revealed that there are three major groups of FtsH proteases originating from gene duplication events in the last common ancestor of bacteria, and that the FtsH proteases involved in PSII repair form a distinct clade branching out before the divergence of FtsH proteases found in all groups of anoxygenic phototrophic bacteria. The word ‚photosynthetic“ was omitted in the following sentence: Instead of We conclude that the phylogeny of FtsH proteases is consistent with an early origin of water oxidation chemistry. It should read We conclude that the phylogeny of FtsH proteases is consistent with an early origin of photosynthetic water oxidation chemistry. Introduction: The words ‚reactions“ and ‚for“ were used mistakenly in the following paragraph: Instead of Oxygenic photosynthetic electron transport from water to NADP + requires the participation of two functionally distinct reactions centers (RCs) acting in series: photosystem II (PSII, a Type II RC containing quinone electron acceptors) and photosystem I (PSI, a Type I RC containing redox-active iron-sulphur clusters). Early ideas on for the emergence of oxygenic photosynthesis focused on the evolution of PSI and PSII from pre-existing RCs found in anoxygenic photosynthetic bacteria (Nitschke and Rutherford 1991) and the horizontal transfer of genes encoding chlo
Beckova M, Yu J, Krynicka V, et al., 2017, Structure of Psb29/Thf1 and its association with the FtsH protease complex involved in photosystem II repair in cyanobacteria, Philosophical Transactions of the Royal Society B: Biological Sciences, Vol: 372, ISSN: 1471-2970
One strategy for enhancing photosynthesis in crop plants is to improve the ability to repair photosystem II (PSII) in response to irreversible damage by light. Despite the pivotal role of thylakoid embedded FtsH protease complexes in the selective degradation of PSII subunits during repair, little is known about the factors involved in regulating FtsH expression. Here we show using the cyanobacterium Synechocystis sp. PCC 6803 that the Psb29 subunit, originally identified as a minor component of His tagged PSII preparations, physically interacts with FtsH complexes in vivo and is required for normal accumulation of the FtsH2/FtsH3 hetero oligomeric complex involved in PSII repair. We show using X ray crystallography that Psb29 from Thermosynechococcus elongatushas a unique fold consisting of a helical bundle and an extended C terminal helix and contains a highly conserved region that might be involved in binding to FtsH. A similar interaction is likely to occur in Arabidopsis chloroplasts between the Psb29 homologue, termed THF1, and the FTSH2/FTSH5 complex. The direct involvement of Psb29/THF1 in FtsH accumulation helps explain why THF1 is a target during the hypersensitive response in plants induced by pathogen infection. Downregulating FtsH function and the PSII repair cycle via THF1 would contribute to the production
Krynická V, Shao S, Nixon PJ, et al., 2015, Accessibility controls selective degradation ofphotosystem II subunits by FtsH protease, Nature Plants, Vol: 1, ISSN: 2055-0278
The oxygen-evolving photosystem II (PSII) complex located inchloroplasts and cyanobacteria is sensitive to light-induceddamage1 that unless repaired causes reduction in photosyntheticcapacity and growth. Although a potential target forcrop improvement, the mechanism of PSII repair remainsunclear. The D1 reaction center protein is the main target forphotodamage2, with repair involving the selective degradationof the damaged protein by FtsH protease3. How a singledamaged PSII subunit is recognized for replacement isunknown. Here, we have tested the dark stability of PSII subunitsin strains of the cyanobacterium Synechocystis PCC6803 blocked at specific stages of assembly. We have foundthat when D1, which is normally shielded by the CP43subunit, becomes exposed in a photochemically active PSIIcomplex lacking CP43, it is selectively degraded by FtsH evenin the dark. Removal of the CP47 subunit, which increasesaccessibility of FtsH to the D2 subunit, induced dark degradationof D2 at a faster rate than that of D1. In contrast,CP47 and CP43 are resistant to degradation in the dark. Ourresults indicate that protease accessibility induced by PSII disassemblyis an important determinant in the selection of the D1and D2 subunits to be degraded by FtsH.
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