Mobility of the Primary Electron-Accepting Plastoquinone QAof Photosystem II in aSynechocystissp. PCC 6803 Strain Carrying Mutations in the D2 Protein†

Biochemistry ◽  
1998 ◽  
Vol 37 (33) ◽  
pp. 11569-11578 ◽  
Author(s):  
Svetlana Ermakova-Gerdes ◽  
Wim Vermaas
Keyword(s):  
Photosystem Ii ◽  
Primary Electron ◽  
D2 Protein ◽  
Pcc 6803

scholarly journals Slr2013 Is a Novel Protein Regulating Functional Assembly of Photosystem II in Synechocystis sp. Strain PCC 6803

2003 ◽  
Vol 185 (22) ◽  
pp. 6615-6623 ◽  
Author(s):  
Galyna I. Kufryk ◽  
Wim F. J. Vermaas
Keyword(s):  
Photosystem Ii ◽  
Critical Role ◽  
Hypothetical Protein ◽  
Primary Electron ◽  
Reaction Centers ◽  
Photoautotrophic Growth ◽  
Redox Active ◽  
Pcc 7120 ◽  
D2 Protein ◽  
Pcc 6803

ABSTRACT The Synechocystis sp. strain PCC 6803, which has a T192H mutation in the D2 protein of photosystem II, is an obligate photoheterotroph due to the lack of assembled photosystem II complexes. A secondary mutant, Rg2, has been selected that retains the T192H mutation but is able to grow photoautotrophically. Restoration of photoautotrophic growth in this mutant was caused by early termination at position 294 in the Slr2013 protein. The T192H mutant with truncated Slr2013 forms fully functional photosystem II reaction centers that differ from wild-type reaction centers only by a 30% higher rate of charge recombination between the primary electron acceptor, QA −, and the donor side and by a reduced stability of the oxidized form of the redox-active Tyr residue, YD, in the D2 protein. This suggests that the T192H mutation itself did not directly affect electron transfer components, but rather affected protein folding and/or stable assembly of photosystem II, and that Slr2013 is involved in the folding of the D2 protein and the assembly of photosystem II. Besides participation in photosystem II assembly, Slr2013 plays a critical role in the cell, because the corresponding gene cannot be deleted completely under conditions in which photosystem II is dispensable. Truncation of Slr2013 by itself does not affect photosynthetic activity of Synechocystis sp. strain PCC 6803. Slr2013 is annotated in CyanoBase as a hypothetical protein and shares a DUF58 family signature with other hypothetical proteins of unknown function. Genes for close homologues of Slr2013 are found in other cyanobacteria (Nostoc punctiforme, Anabaena sp. strain PCC 7120, and Thermosynechococcus elongatus BP-1), and apparent orthologs of this protein are found in Eubacteria and Archaea, but not in eukaryotes. We suggest that Slr2013 regulates functional assembly of photosystem II and has at least one other important function in the cell.

scholarly journals Targeted Random Mutagenesis To Identify Functionally Important Residues in the D2 Protein of Photosystem II in Synechocystis sp. Strain PCC 6803

2001 ◽  
Vol 183 (1) ◽  
pp. 145-154 ◽  
Author(s):  
Svetlana Ermakova-Gerdes ◽  
Zhenbao Yu ◽  
Wim Vermaas
Keyword(s):  
Photosystem Ii ◽  
Screening Method ◽  
Random Mutagenesis ◽  
Terminal Part ◽  
Photoautotrophic Growth ◽  
Intragenic Complementation ◽  
Novel Method ◽  
Α Helix ◽  
D2 Protein ◽  
Pcc 6803

ABSTRACT To identify important residues in the D2 protein of photosystem II (PSII) in the cyanobacterium Synechocystis sp. strain PCC 6803, we randomly mutagenized a region of psbDI (coding for a 96-residue-long C-terminal part of D2) with sodium bisulfite. Mutagenized plasmids were introduced into a Synechocystissp. strain PCC 6803 mutant that lacks both psbD genes, and mutants with impaired PSII function were selected. Nine D2 residues were identified that are important for PSII stability and/or function, as their mutation led to impairment of photoautotrophic growth. Five of these residues are likely to be involved in the formation of the QA-binding niche; these are Ala249, Ser254, Gly258, Ala260, and His268. Three others (Gly278, Ser283, and Gly288) are in transmembrane α-helix E, and their alteration leads to destabilization of PSII but not to major functional alterations of the remaining centers, indicating that they are unlikely to interact directly with cofactors. In the C-terminal lumenal tail of D2, only one residue (Arg294) was identified as functionally important for PSII. However, from the number of mutants generated it is likely that most or all of the 70 residues that are susceptible to bisulfite mutagenesis have been altered at least once. The fact that mutations in most of these residues have not been picked up by our screening method suggests that these mutations led to a normal photoautotrophic phenotype. A novel method of intragenic complementation in Synechocystissp. strain PCC 6803 was developed to facilitate genetic analysis ofpsbDI mutants containing several amino acid changes in the targeted domain. Recombination between genome copies in the same cell appears to be much more prevalent in Synechocystis sp. strain PCC 6803 than was generally assumed.

scholarly journals A reversibly induced CRISPRi system targeting Photosystem II in the cyanobacterium Synechocystis sp. PCC 6803

2020 ◽  
Author(s):  
Deng Liu ◽  
Virginia M. Johnson ◽  
Himadri B. Pakrasi
Keyword(s):  
Photosystem Ii ◽  
Sole Carbon Source ◽  
Model Organism ◽  
Inducible Promoter ◽  
New Strategy ◽  
Photosynthetic Complexes ◽  
Promoter System ◽  
Synechocystis Sp ◽  
D2 Protein ◽  
Pcc 6803

ABSTRACTThe cyanobacterium Synechocystis sp. PCC 6803 is used as a model organism to study photosynthesis, as it can utilize glucose as the sole carbon source to support its growth under heterotrophic conditions. CRISPR interference (CRISPRi) has been widely applied to repress the transcription of genes in a targeted manner in cyanobacteria. However, a robust and reversible induced CRISPRi system has not been explored in Synechocystis 6803 to knock down and recover the expression of a targeted gene. In this study, we built a tightly controlled chimeric promoter, PrhaBAD-RSW, in which a theophylline responsive riboswitch was integrated into a rhamnose-inducible promoter system. We applied this promoter to drive the expression of ddCpf1 (DNase-dead Cpf1 nuclease) in a CRISPRi system and chose the PSII reaction center gene psbD (D2 protein) to target for repression. psbD was specifically knocked down by over 95% of its native expression, leading to severely inhibited Photosystem II activity and growth of Synechocystis 6803 under photoautotrophic conditions. Significantly, removal of the inducers rhamnose and theophylline reversed repression by CRISPRi. Expression of PsbD recovered following release of repression, coupled with increased Photosystem II content and activity. This reversibly induced CRISPRi system in Synechocystis 6803 represents a new strategy for study of the biogenesis of photosynthetic complexes in cyanobacteria.

scholarly journals Photosystem II antenna modules CP43 and CP47 do not form a stable ‘no reaction centre complex’ in the cyanobacterium Synechocystis sp. PCC 6803

2022 ◽  
Author(s):  
Martina Bečková ◽  
Roman Sobotka ◽  
Josef Komenda
Keyword(s):  
Photosystem Ii ◽  
High Light ◽  
Oxygenic Photosynthesis ◽  
Reaction Centre ◽  
Wild Type ◽  
Migration Patterns ◽  
Separate Protein ◽  
Antenna Module ◽  
D2 Protein ◽  
Pcc 6803

AbstractThe repair of photosystem II is a key mechanism that keeps the light reactions of oxygenic photosynthesis functional. During this process, the PSII central subunit D1 is replaced with a newly synthesized copy while the neighbouring CP43 antenna with adjacent small subunits (CP43 module) is transiently detached. When the D2 protein is also damaged, it is degraded together with D1 leaving both the CP43 module and the second PSII antenna module CP47 unassembled. In the cyanobacterium Synechocystis sp. PCC 6803, the released CP43 and CP47 modules have been recently suggested to form a so-called no reaction centre complex (NRC). However, the data supporting the presence of NRC can also be interpreted as a co-migration of CP43 and CP47 modules during electrophoresis and ultracentrifugation without forming a mutual complex. To address the existence of NRC, we analysed Synechocystis PSII mutants accumulating one or both unassembled antenna modules as well as Synechocystis wild-type cells stressed with high light. The obtained results were not compatible with the existence of a stable NRC since each unassembled module was present as a separate protein complex with a mutually similar electrophoretic mobility regardless of the presence of the second module. The non-existence of NRC was further supported by isolation of the His-tagged CP43 and CP47 modules from strains lacking either D1 or D2 and their migration patterns on native gels.

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