1
|
Zharmukhamedov SK, Shabanova MS, Rodionova MV, Huseynova IM, Karacan MS, Karacan N, Aşık KB, Kreslavski VD, Alwasel S, Allakhverdiev SI. Effects of Novel Photosynthetic Inhibitor [CuL2]Br2 Complex on Photosystem II Activity in Spinach. Cells 2022; 11:cells11172680. [PMID: 36078088 PMCID: PMC9455146 DOI: 10.3390/cells11172680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/25/2022] Open
Abstract
The effects of the novel [CuL2]Br2 complex (L = bis{4H-1,3,5-triazino [2,1-b]benzothiazole-2-amine,4-(2-imidazole)}copper(II) bromide complex) on the photosystem II (PSII) activity of PSII membranes isolated from spinach were studied. The absence of photosynthetic oxygen evolution by PSII membranes without artificial electron acceptors, but in the presence of [CuL2]Br2, has shown that it is not able to act as a PSII electron acceptor. In the presence of artificial electron acceptors, [CuL2]Br2 inhibits photosynthetic oxygen evolution. [CuL2]Br2 also suppresses the photoinduced changes of the PSII chlorophyll fluorescence yield (FV) related to the photoreduction of the primary quinone electron acceptor, QA. The inhibition of both characteristic PSII reactions depends on [CuL2]Br2 concentration. At all studied concentrations of [CuL2]Br2, the decrease in the FM level occurs exclusively due to a decrease in Fv. [CuL2]Br2 causes neither changes in the F0 level nor the retardation of the photoinduced rise in FM, which characterizes the efficiency of the electron supply from the donor-side components to QA through the PSII reaction center (RC). Artificial electron donors (sodium ascorbate, DPC, Mn2+) do not cancel the inhibitory effect of [CuL2]Br2. The dependences of the inhibitory efficiency of the studied reactions of PSII on [CuL2]Br2 complex concentration practically coincide. The inhibition constant Ki is about 16 µM, and logKi is 4.8. As [CuL2]Br2 does not change the aromatic amino acids’ intrinsic fluorescence of the PSII protein components, it can be proposed that [CuL2]Br2 has no significant effect on the native state of PSII proteins. The results obtained in the present study are compared to the literature data concerning the inhibitory effects of PSII Cu(II) aqua ions and Cu(II)-organic complexes.
Collapse
Affiliation(s)
- Sergey K. Zharmukhamedov
- Institute of Basic Biological Problems, FRC PSCBR RAS, 142290 Pushchino, Russia
- Correspondence: (S.K.Z.); (S.I.A.)
| | - Mehriban S. Shabanova
- Bionanotechnology Laboratory, Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences, AZ1073 Baku, Azerbaijan
| | - Margarita V. Rodionova
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, 127276 Moscow, Russia
| | - Irada M. Huseynova
- Bionanotechnology Laboratory, Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences, AZ1073 Baku, Azerbaijan
| | - Mehmet Sayım Karacan
- Department of Chemistry, Science Faculty, Gazi University, Teknikokullar, Ankara 06500, Turkey
| | - Nurcan Karacan
- Department of Chemistry, Science Faculty, Gazi University, Teknikokullar, Ankara 06500, Turkey
| | - Kübra Begüm Aşık
- Department of Chemistry, Science Faculty, Gazi University, Teknikokullar, Ankara 06500, Turkey
| | | | - Saleh Alwasel
- College of Science, King Saud University, Riyadh 12372, Saudi Arabia
| | - Suleyman I. Allakhverdiev
- Institute of Basic Biological Problems, FRC PSCBR RAS, 142290 Pushchino, Russia
- Bionanotechnology Laboratory, Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences, AZ1073 Baku, Azerbaijan
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, 127276 Moscow, Russia
- Department of Plant Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119991 Moscow, Russia
- Correspondence: (S.K.Z.); (S.I.A.)
| |
Collapse
|
2
|
Forsman JA, Eaton‐Rye JJ. The D1:Ser268 residue of Photosystem II contributes to an alternative pathway for Q
B
protonation in the absence of bound bicarbonate. FEBS Lett 2020; 594:2953-2964. [DOI: 10.1002/1873-3468.13880] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 11/07/2022]
Affiliation(s)
- Jack A. Forsman
- Department of Biochemistry University of Otago Dunedin New Zealand
| | | |
Collapse
|
3
|
Robescu MS, Rubini R, Beneventi E, Tavanti M, Lonigro C, Zito F, Filippini F, Cendron L, Bergantino E. From the Amelioration of a NADP
+
‐dependent Formate Dehydrogenase to the Discovery of a New Enzyme: Round Trip from Theory to Practice. ChemCatChem 2020. [DOI: 10.1002/cctc.201902089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Marina Simona Robescu
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Rudy Rubini
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Elisa Beneventi
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Michele Tavanti
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Chiara Lonigro
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires UMR7099, CNRS, IBPC, Université Paris Diderot Sorbonne Paris Cité 13 rue Pierre et Marie Curie 75005 Paris France
| | - Francesca Zito
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires UMR7099, CNRS, IBPC, Université Paris Diderot Sorbonne Paris Cité 13 rue Pierre et Marie Curie 75005 Paris France
| | - Francesco Filippini
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Laura Cendron
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| | - Elisabetta Bergantino
- Synthetic Biology and Biotechnology Unit Department of Biology University of Padova via U. Bassi 58B/viale G. Colombo 3 I-35131 Padova Italy
| |
Collapse
|
4
|
Govindjee. A sixty-year tryst with photosynthesis and related processes: an informal personal perspective. PHOTOSYNTHESIS RESEARCH 2019; 139:15-43. [PMID: 30343396 DOI: 10.1007/s11120-018-0590-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
After briefly describing my early collaborative work at the University of Allahabad, that had laid the foundation of my research life, I present here some of our research on photosynthesis at the University of Illinois at Urbana-Champaign, randomly selected from light absorption to NADP+ reduction in plants, algae, and cyanobacteria. These include the fact that (i) both the light reactions I and II are powered by light absorbed by chlorophyll (Chl) a of different spectral forms; (ii) light emission (fluorescence, delayed fluorescence, and thermoluminescence) by plants, algae, and cyanobacteria provides detailed information on these reactions and beyond; (iii) primary photochemistry in both the photosystems I (PS I) and II (PS II) occurs within a few picoseconds; and (iv) most importantly, bicarbonate plays a unique role on the electron acceptor side of PS II, specifically at the two-electron gate of PS II. Currently, the ongoing research around the world is, and should be, directed towards making photosynthesis better able to deal with the global issues (such as increasing population, dwindling resources, and rising temperature) particularly through genetic modification. However, basic research is necessary to continue to provide us with an understanding of the molecular mechanism of the process and to guide us in reaching our goals of increasing food production and other chemicals we need for our lives.
Collapse
|
5
|
Swirsky Whitney LA, Novi G, Perata P, Loreti E. Distinct mechanisms regulating gene expression coexist within the fermentative pathways in Chlamydomonas reinhardtii. ScientificWorldJournal 2012; 2012:565047. [PMID: 22792045 PMCID: PMC3385630 DOI: 10.1100/2012/565047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 03/21/2012] [Indexed: 12/12/2022] Open
Abstract
Under dark anoxia, the unicellular green algae Chlamydomonas reinhardtii may produce hydrogen by means of its hydrogenase enzymes, in particular HYD1, using reductants derived from the degradation of intercellular carbon stores. Other enzymes belonging to the fermentative pathways compete for the same reductants. A complete understanding of the mechanisms determining the activation of one pathway rather than another will help us engineer Chlamydomonas for fermentative metabolite production, including hydrogen. We examined the expression pattern of the fermentative genes PDC3, LDH1, ADH2, PFL1, and PFR1 in response to day-night cycles, continuous light, continuous darkness, and low or high oxygen availability, which are all conditions that vary on a regular basis in Chlamydomonas' natural environment. We found that all genes except PFL1 show daily fluctuations in expression, and that PFR1 differentiated itself from the others in that it is clearly responsive to low oxygen, where as PDC3, LDH1, and ADH2 are primarily under diurnal regulation. Our results provide evidence that there exist at least three different regulatory mechanisms within the fermentative pathways and suggest that the fermentative pathways are not redundant but rather that availability of a variety of pathways allows for a differential metabolic response to different environmental conditions.
Collapse
|
6
|
Shevela D, Eaton-Rye JJ, Shen JR, Govindjee. Photosystem II and the unique role of bicarbonate: a historical perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1134-51. [PMID: 22521596 DOI: 10.1016/j.bbabio.2012.04.003] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Revised: 04/05/2012] [Accepted: 04/06/2012] [Indexed: 12/11/2022]
Abstract
In photosynthesis, cyanobacteria, algae and plants fix carbon dioxide (CO(2)) into carbohydrates; this is necessary to support life on Earth. Over 50 years ago, Otto Heinrich Warburg discovered a unique stimulatory role of CO(2) in the Hill reaction (i.e., O(2) evolution accompanied by reduction of an artificial electron acceptor), which, obviously, does not include any carbon fixation pathway; Warburg used this discovery to support his idea that O(2) in photosynthesis originates in CO(2). During the 1960s, a large number of researchers attempted to decipher this unique phenomenon, with limited success. In the 1970s, Alan Stemler, in Govindjee's lab, perfected methods to get highly reproducible results, and observed, among other things, that the turnover of Photosystem II (PSII) was stimulated by bicarbonate ions (hydrogen carbonate): the effect would be on the donor or the acceptor, or both sides of PSII. In 1975, Thomas Wydrzynski, also in Govindjee's lab, discovered that there was a definite bicarbonate effect on the electron acceptor (the plastoquinone) side of PSII. The most recent 1.9Å crystal structure of PSII, unequivocally shows HCO(3)(-) bound to the non-heme iron that sits in-between the bound primary quinone electron acceptor, Q(A), and the secondary quinone electron acceptor Q(B). In this review, we focus on the historical development of our understanding of this unique bicarbonate effect on the electron acceptor side of PSII, and its mechanism as obtained by biochemical, biophysical and molecular biological approaches in many laboratories around the World. We suggest an atomic level model in which HCO(3)(-)/CO(3)(2-) plays a key role in the protonation of the reduced Q(B). In addition, we make comments on the role of bicarbonate on the donor side of PSII, as has been extensively studied in the labs of Alan Stemler (USA) and Vyacheslav Klimov (Russia). We end this review by discussing the uniqueness of bicarbonate's role in oxygenic photosynthesis and its role in the evolutionary development of O(2)-evolving PSII. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
Collapse
Affiliation(s)
- Dmitriy Shevela
- Centre for Organelle Research, University of Stavanger, Stavanger, Norway.
| | | | | | | |
Collapse
|
7
|
Pobeguts OV, Smolova TN, Klimov VV. Bicarbonate stabilizes isolated D1/D2/cytochrome b559 complex of photosystem 2 against thermoinactivation. BIOCHEMISTRY. BIOKHIMIIA 2012; 77:171-9. [PMID: 22348477 DOI: 10.1134/s0006297912020083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
It has been shown that thermoinactivation of the isolated D1/D2/cytochrome b(559) complex (RC) of photosystem 2 (PS-2) from pea under anaerobic conditions at 35°C in 20 mM Tris-HCl buffer (pH 7.2) depleted of HCO(3)(-), with 35 mM NaCl and 0.05% n-dodecyl-β-maltoside, results in a decrease in photochemical activity measured by photoreduction of the PS-2 primary electron acceptor, pheophytin (by 50% after 3 min of heating), which is accompanied by aggregation of the D1 and D2 proteins. Bicarbonate, formate, and acetate anions added to the sample under these conditions differently influence the maintenance of photochemical activity: a 50% loss of photochemical activity occurs in 11.5 min of heating in the presence of bicarbonate and in 4 and 4.6 min in the presence of formate and acetate, respectively. The addition of bicarbonate completely prevents aggregation of the D1 and D2 proteins as opposed to formate and acetate (their presence has no effect on the aggregation during thermoinactivation). Since the isolated RCs have neither inorganic Mn/Ca-containing core of the water-oxidizing complex nor nonheme Fe(2+), it is supposed that bicarbonate specifically interacts with the hydrophilic domains of the D1 and D2 proteins, which prevents their structural modification that is a signal for aggregation of these proteins and the loss of photochemical activity.
Collapse
Affiliation(s)
- O V Pobeguts
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
| | | | | |
Collapse
|
8
|
|
9
|
Perrine Z, Sayre R. Modulating the Redox Potential of the Stable Electron Acceptor, QB, in Mutagenized Photosystem II Reaction Centers. Biochemistry 2011; 50:1454-64. [DOI: 10.1021/bi1017649] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zoee Perrine
- The Ohio State University Biophysics Program, Columbus, Ohio 43210, United States
- The Donald Danforth Plant Science Center, St. Louis, Missouri 63132, United States
| | - Richard Sayre
- The Donald Danforth Plant Science Center, St. Louis, Missouri 63132, United States
| |
Collapse
|
10
|
Pavlovič A. Spatio-temporal changes of photosynthesis in carnivorous plants in response to prey capture, retention and digestion. PLANT SIGNALING & BEHAVIOR 2010; 5:1325-9. [PMID: 20523127 PMCID: PMC3115228 DOI: 10.4161/psb.5.11.11906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 03/26/2010] [Accepted: 03/26/2010] [Indexed: 05/29/2023]
Abstract
Carnivorous plants have evolved modified leaves into the traps which assist in nutrient uptake from captured prey. It is known that the traps of carnivorous plants have usually lower photosynthetic rates than assimilation leaves as a result of adaptation to carnivory. However a few recent studies have indicated that photosynthesis and respiration undergo spatio-temporal changes during prey capture and retention, especially in the genera with active trapping mechanisms. This study describes the spatio-temporal changes of effective quantum yield of photochemical energy conversion in photosystem II (Ф PSII) in response to ant-derived formic acid during its capture and digestion.
Collapse
Affiliation(s)
- Andrej Pavlovič
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia.
| |
Collapse
|
11
|
Rose S, Minagawa J, Seufferheld M, Padden S, Svensson B, Kolling DRJ, Crofts AR, Govindjee. D1-arginine257 mutants (R257E, K, and Q) of Chlamydomonas reinhardtii have a lowered QB redox potential: analysis of thermoluminescence and fluorescence measurements. PHOTOSYNTHESIS RESEARCH 2008; 98:449-68. [PMID: 18777103 PMCID: PMC2978033 DOI: 10.1007/s11120-008-9351-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 08/06/2008] [Indexed: 05/08/2023]
Abstract
Arginine257 (R257), in the de-helix that caps the Q(B) site of the D1 protein, has been shown by mutational studies to play a key role in the sensitivity of Photosystem II (PS II) to bicarbonate-reversible binding of the formate anion. In this article, the role of this residue has been further investigated through D1 mutations (R257E, R257Q, and R257K) in Chlamydomonas reinhardtii. We have investigated the activity of the Q(B) site by studying differences from wild type on the steady-state turnover of PS II, as assayed through chlorophyll (Chl) a fluorescence yield decay after flash excitation. The effects of p-benzoquinone (BQ, which oxidizes reduced Q(B), Q(B)(-) ) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU, which blocks electron flow from Q(A)(-) to Q(B)) were measured. The equilibrium constants of the two-electron gate were obtained through thermoluminescence measurements. The thermoluminescence properties were changed in the mutants, especially when observed after pretreatment with 100 microM BQ. A theoretical analysis of the thermoluminescence data, based mainly on the recombination pathways model of Rappaport et al. (2005), led to the conclusion that the free-energy difference for the recombination of Q(B)(-) with S(2) was reduced by 20-40 mV in the three mutants (D1-R257K, D1-R257Q, and D1-R257E); this was interpreted to be due to a lowering of the redox potential of Q(B)/Q(B)(-). Further, since the recombination of Q(A)(-) with S(2) was unaffected, we suggest that no significant change in redox potential of Q(A)/Q(A)(-) occurred in these three mutants. The maximum variable Chl a fluorescence yield is lowered in the mutants, in the order R257K > R257Q > R257E, compared to wild type. Our analysis of the binary oscillations in Chl a fluorescence following pretreatment of cells with BQ showed that turnover of the Q(B) site was relatively unaffected in the three mutants. The mutant D1-R257E had the lowest growth rate and steady-state activity and showed the weakest binary oscillations. We conclude that the size and the charge of the amino acid at the position D1-257 play a role in PS II function by modulating the effective redox potential of the Q(B)/Q(B)(-) pair. We discuss an indirect mechanism mediated through electrostatic and/or surface charge effects and the possibility of more pleiotropic effects arising from decreased stability of the D1/D2 and D1/CP47 interfaces.
Collapse
Affiliation(s)
- Stuart Rose
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Shevela D, Klimov V, Messinger J. Interactions of photosystem II with bicarbonate, formate and acetate. PHOTOSYNTHESIS RESEARCH 2007; 94:247-64. [PMID: 17653834 DOI: 10.1007/s11120-007-9200-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 05/16/2007] [Indexed: 05/16/2023]
Abstract
In this study, we probe the effects of bicarbonate (hydrogencarbonate), BC, removal from photosystem II in spinach thylakoids by measuring flash-induced oxygen evolution patterns (FIOPs) with a Joliot-type electrode. For this we compared three commonly employed methods: (1) washing in BC-free medium, (2) formate addition, and (3) acetate addition. Washing of the samples with buffers depleted of BC and CO2 by bubbling with argon (Method 1) under our conditions leads to an increase in the double hit parameter of the first flash (beta 1), while the miss parameter and the overall activity remain unchanged. In contrast, addition of 40-50 mM formate or acetate results in a significant increase in the miss parameter and to an approximately 50% (formate) and approximately 10% (acetate) inhibition of the overall oxygen evolution activity, but not to an increased beta 1 parameter. All described effects could be reversed by washing with formate/acetate free buffer and/or addition of 2-10 mM bicarbonate. The redox potential of the water-oxidizing complex (WOC) in samples treated by Method 1 is compared to samples containing 2 mM bicarbonate in two ways: (1) The lifetimes of the S0, S2, and S3 states were measured, and no differences were found between the two sample types. (2) The S1, S0, S(-1), and S(-2) states were probed by incubation with small concentrations of NH2OH. These experiments displayed a subtle, yet highly reproducible difference in the apparent Si/S(-i) state distribution which is shown to arise from the interaction of BC with PSII in the already reduced states of the WOC. These data are discussed in detail by also taking into account the CO2 concentrations present in the buffers after argon bubbling and during the measurements. These values were measured by membrane-inlet mass spectrometry (MIMS).
Collapse
Affiliation(s)
- Dmitriy Shevela
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | | | | |
Collapse
|
13
|
Makarova VV, Kosourov S, Krendeleva TE, Semin BK, Kukarskikh GP, Rubin AB, Sayre RT, Ghirardi ML, Seibert M. Photoproduction of hydrogen by sulfur-deprived C. reinhardtii mutants with impaired photosystem II photochemical activity. PHOTOSYNTHESIS RESEARCH 2007; 94:79-89. [PMID: 17701084 DOI: 10.1007/s11120-007-9219-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Accepted: 07/03/2007] [Indexed: 05/16/2023]
Abstract
Photoproduction of H2 was examined in a series of sulfur-deprived Chlamydomonas reinhardtii D1-R323 mutants with progressively impaired PSII photochemical activity. In the R323H, R323D, and R323E D1 mutants, replacement of arginine affects photosystem II (PSII) function, as demonstrated by progressive decreases in O2-evolving activity and loss of PSII photochemical activity. Significant changes in PSII activity were found when the arginine residue was replaced by negatively charged amino acid residues (R323D and R323E). However, the R323H (positively charged or neutral, depending on the ambient pH) mutant had minimal changes in PSII activity. The R323H, R323D, and R323E mutants and the pseudo-wild-type (pWt) with restored PSII function were used to study the effects of sulfur deprivation on H2-production activity. All of these mutants exhibited significant changes in the normal parameters associated with the H2-photoproduction process, such as a shorter aerobic phase, lower accumulation of starch, a prolonged anaerobic phase observed before the onset of H2-production, a shorter duration of H2-production, lower H2 yields compared to the pWt control, and slightly higher production of dark fermentation products such as acetate and formate. The more compromised the PSII photochemical activity, the more dramatic was the effect of sulfur deprivation on the H2-production process, which depends both on the presence of residual PSII activity and the amount of stored starch.
Collapse
Affiliation(s)
- Valeria V Makarova
- National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
El-Bestawy EA, El-Salam AZA, Mansy AERH. Potential use of environmental cyanobacterial species in bioremediation of lindane-contaminated effluents. INTERNATIONAL BIODETERIORATION & BIODEGRADATION 2007; 59:180-192. [DOI: 10.1016/j.ibiod.2006.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
|
15
|
|