A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700

Redding, Kevin; MacMillan, Fraser; Leibl, Winfried; Brettel, Klaus; Hanley, Jonathan; Rutherford, A. William; Breton, Jacques; Rochaix, Jean David

doi:10.1093/emboj/17.1.50

Cited by 102 publications

(106 citation statements)

References 66 publications

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“…The corresponding change to the axial ligand of P M in the purple bacterial reaction center resulted in replacement of bacteriochlorophyll with bacteriopheophytin and consequent localization of the triplet to the BChl half (50). Although it is not clear whether the PsaB-H656L mutation results in replacement of Chl with pheophytin, the severe perturbation of the properties of P 700 in this mutant is consistent with this hypothesis (18,34,43,51). If this were the case, then one would expect localization of the triplet to P A in the PsaB-H656L mutant.…”

Section: Summary Of Resultsmentioning

confidence: 66%

Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I

Lucas

Konovalova

et al. 2004

Biochemistry

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The primary electron donor of photosystem I (PS1), called P 700 , is a heterodimer of chlorophyll (Chl) a and a′. The crystal structure of photosystem I reveals that the chlorophyll a′ (P A ) could be hydrogenbonded to the protein via a threonine residue, while the chlorophyll a (P B ) does not have such a hydrogen bond. To investigate the influence of this hydrogen bond on P 700 , PsaA-Thr739 was converted to alanine to remove the H-bond to the 13 1 -keto group of the chlorophyll a′ in Chlamydomonas reinhardtii. The PsaA-T739A mutant was capable of assembling active PS1. Furthermore the mutant PS1 contained approximately one chlorophyll a′ molecule per reaction center, indicating that P 700 was still a Chl a/a′ heterodimer in the mutant. However, the mutation induced several band shifts in the visible P 700 + -P 700 absorbance difference spectrum. Redox titration of P 700 revealed a 60 mV decrease in the P 700 /P 700 + midpoint potential of the mutant, consistent with loss of a H-bond. Fourier transform infrared (FTIR) spectroscopy indicates that the ground state of P 700 is somewhat modified by mutation of ThrA739 to alanine. Comparison of FTIR difference band shifts upon P 700 + formation in WT and mutant PS1 suggests that the mutation modifies the charge distribution over the pigments in the P 700 + state, with ∼14-18% of the positive charge on P B in WT being relocated onto P A in the mutant. 1 H-electron-nuclear double resonance (ENDOR) analysis of the P 700 + cation radical was also consistent with a slight redistribution of spin from the P B chlorophyll to P A , as well as some redistribution of spin within the P B chlorophyll. High-field electron paramagnetic resonance (EPR) spectroscopy at 330-GHz was used to resolve the g-tensor of P 700 + , but no significant differences from wild-type were observed, except for a slight decrease of anisotropy. The mutation did, however, provoke changes in the zero-field splitting parameters of the triplet state of P 700 ( 3 P 700 ), as determined by EPR. Interestingly, the mutation-induced change in asymmetry of P 700 did not cause an observable change in the directionality of electron transfer within PS1.In higher plants and green algae, the photosynthetic reaction occurs within two large pigment-protein complexes located in the thylakoid membranes of the chloroplast: photosystems I and II (PS1 and PS2). 1 These two systems exemplify the type 1 ("iron-sulfur") and type 2 ("quinone") reaction centers, respectively, based on their terminal electron acceptors. In oxygenic phototrophs, PS2 and PS1 act in tandem to oxidize water and reduce NADP + , but there are several anoxygenic photosynthetic bacteria that use only one type of reaction center protein.All known reaction centers share a similar structural motif with a core of reaction centers composed of two similar or identical integral membrane subunits, to which the various redox cofactors are bound. Both the protein structural motifs and the cofactor arrangements are characterized by a pseudo-C 2 symmetry ...

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Section: Summary Of Resultsmentioning

confidence: 66%

Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I

Lucas

Konovalova

et al. 2004

Biochemistry

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“…Additional proteins that are induced under anaerobic conditions and associate with PSI may represent novel candidates mediating this unsolved regulation of CEF. To test whether ANR1, which is induced in expression under anoxic settings (18), is such a candidate, we investigated the accumulation of ANR1 in a PSIdeficient mutant (19). Accumulation of ANR1 is diminished in the absence of PSI under anaerobic conditions (Fig.…”

Section: Anr1 Cas and Pgrl1 Are Associated Together In A Psi-dependentmentioning

confidence: 99%

Calcium-dependent regulation of cyclic photosynthetic electron transfer by a CAS, ANR1, and PGRL1 complex

Terashima

Petroutsos

Hüdig

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

147

170

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Cyclic photosynthetic electron flow (CEF) is crucial to photosynthesis because it participates in the control of chloroplast energy and redox metabolism, and it is particularly induced under adverse environmental conditions. Here we report that down-regulation of the chloroplast localized Ca 2+ sensor (CAS) protein by an RNAi approach in Chlamydomonas reinhardtii results in strong inhibition of CEF under anoxia. Importantly, this inhibition is rescued by an increase in the extracellular Ca 2+ concentration, inferring that CEF is Ca 2+ -dependent. Furthermore, we identified a protein, anaerobic response 1 (ANR1), that is also required for effective acclimation to anaerobiosis. Depletion of ANR1 by artificial microRNA expression mimics the CAS-depletion phenotype, and under anaerobic conditions the two proteins coexist within a large active photosystem I-cytochrome b 6 /f complex. Moreover, we provide evidence that CAS and ANR1 interact with each other as well as with PGR5-Like 1 (PGRL1) in vivo. Overall our data establish a Ca 2+ -dependent regulation of CEF via the combined function of ANR1, CAS, and PGRL1, associated with each other in a multiprotein complex.

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“…The total protein on the membrane was visualized by amido black staining, and the membrane was blocked in Trisbuffered saline Tween (TBST; 20 mM Tris, pH 7.5, 150 mM NaCl, and 1% [v/v] Tween 20) supplemented with 5% (w/v) nonfat milk for 1 h. The membrane was incubated with primary antibody in TBST and 1% milk. The primary antisera (and their sources) were as follows: monoclonal anti-HA (Covance; MMS-101R), antiphospho-Lhcb2 (Agrisera; AS13-2705), antiRpl4 (gift of W. Zerges), anti-PsaA (Redding et al, 1998), anti-Cyt f (gift of F.-A. Wollman), anti-PsaC, anti-D1 (gifts of J.-D. Rochaix), anti-Rpl37, and anti-Rps12 (Ramundo et al, 2013).…”

Section: Immunoblottingmentioning

confidence: 99%

A Nucleus-Encoded Chloroplast Phosphoprotein Governs Expression of the Photosystem I Subunit PsaC in Chlamydomonas reinhardtii

Douchi

Longoni

et al. 2016

Plant Cell

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The nucleo-cytoplasmic compartment exerts anterograde control on chloroplast gene expression through numerous proteins that intervene at posttranscriptional steps. Here, we show that the maturation of psaC mutant (mac1) of Chlamydomonas reinhardtii is defective in photosystem I and fails to accumulate psaC mRNA. The MAC1 locus encodes a member of the Half-A-Tetratricopeptide (HAT) family of super-helical repeat proteins, some of which are involved in RNA transactions. The Mac1 protein localizes to the chloroplast in the soluble fraction. MAC1 acts through the 59 untranslated region of psaC transcripts and is required for their stability. Small RNAs that map to the 59end of psaC RNA in the wild type but not in the mac1 mutant are inferred to represent footprints of MAC1-dependent protein binding, and Mac1 expressed in bacteria binds RNA in vitro. A coordinate response to iron deficiency, which leads to dismantling of the photosynthetic electron transfer chain and in particular of photosystem I, also causes a decrease of Mac1. Overexpression of Mac1 leads to a parallel increase in psaC mRNA but not in PsaC protein, suggesting that Mac1 may be limiting for psaC mRNA accumulation but that other processes regulate protein accumulation. Furthermore, Mac 1 is differentially phosphorylated in response to iron availability and to conditions that alter the redox balance of the electron transfer chain.

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A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700

Cited by 102 publications

References 66 publications

Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I

Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I

Calcium-dependent regulation of cyclic photosynthetic electron transfer by a CAS, ANR1, and PGRL1 complex

A Nucleus-Encoded Chloroplast Phosphoprotein Governs Expression of the Photosystem I Subunit PsaC in Chlamydomonas reinhardtii

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A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700

Cited by 102 publications

References 66 publications

Mutation of the Putative Hydrogen-Bond Donor to P700 of Photosystem I

Mutation of the Putative Hydrogen-Bond Donor to P700 of Photosystem I

Calcium-dependent regulation of cyclic photosynthetic electron transfer by a CAS, ANR1, and PGRL1 complex

A Nucleus-Encoded Chloroplast Phosphoprotein Governs Expression of the Photosystem I Subunit PsaC in Chlamydomonas reinhardtii

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Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I

Mutation of the Putative Hydrogen-Bond Donor to P₇₀₀ of Photosystem I