Low Potential Cytochrome C550 Function in Cyanobacteria and Algae

Krogmann, David W.; Smith, Stanley

doi:10.1007/978-94-009-0511-5_379

Cited by 3 publications

(5 citation statements)

References 6 publications

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“…A modest increase in the rate of this cytochrome was observed when ferredoxin II from cyanobacteria was added to the reaction mixture. The specificity for ferredoxin II in the reduction of cyt c550 and the often coincident appearance of ferredoxin II and cyt c550 in cells experiencing dark, anaerobic conditions suggested that these proteins may link carbohydrate breakdown to disposal of electrons in a fermentative pathway [21]. The low E m of this cytochrome was similar to that of cyt c3 of Desulfovibrio desulfuricans [2] and so it could have similar functions.…”

Section: Functionmentioning

confidence: 94%

“…Since cyt c550 was abundant in cells grown on high levels of nitrate and was absent from cells grown on ammonia it was proposed that it could participate in the reduction of nitrate to ammonia [14]. Krogmann and Smith [21] suggested that the function of cyt c550 could be related to anaerobic disposal of electrons from carbohydrate reserves or fermentation to sustain an organism during prolonged dark and anaerobic conditions. A very low rate of cyt c550 enzymatic reduction using NADPH and the spinach ferredoxin: NADP oxidoreductase (FNR) was observed under anaerobic conditions.…”

Section: Functionmentioning

confidence: 99%

“…The emphasis is on the physical properties of the heme and its redox properties. For earlier reviews on cyt c550 see articles by Krogmann [21,22]. Several reviews have been published on photosynthetic soluble cytochromes including cyt c550 [5,23].…”

Section: Introductionmentioning

confidence: 99%

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Photosynthetic cytochrome c550

Roncel

Kirilovsky

Guerrero

et al. 2012

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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Cytochrome c550 (cyt c550) is a membrane component of the PSII complex in cyanobacteria and some eukaryotic algae, such as red and brown algae. Cyt c550 presents a bis-histidine heme coordination which is very unusual for monoheme c-type cytochromes. In PSII, the cyt c550 with the other extrinsic proteins stabilizes the binding of Cl(-) and Ca(2+) ions to the oxygen evolving complex and protects the Mn(4)Ca cluster from attack by bulk reductants. The role (if there is one) of the heme of the cyt c550 is unknown. The low midpoint redox potential (E(m)) of the purified soluble form (from -250 to -314mV) is incompatible with a redox function in PSII. However, more positive values for the Em have been obtained for the cyt c550 bound to the PSII. A very recent work has shown an E(m) value of +200mV. These data open the possibility of a redox function for this protein in electron transfer in PSII. Despite the long distance (22Å) between cyt c550 and the nearest redox cofactor (Mn(4)Ca cluster), an electron transfer reaction between these components is possible. Some kind of protective cycle involving a soluble redox component in the lumen has also been proposed. The aim of this article is to review previous studies done on cyt c550 and to consider its function in the light of the new results obtained in recent years. The emphasis is on the physical properties of the heme and its redox properties. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

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Section: Functionmentioning

confidence: 94%

Section: Functionmentioning

confidence: 99%

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Photosynthetic cytochrome c550

Roncel

Kirilovsky

Guerrero

et al. 2012

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…Ca 2+ and is required for efficient water-splitting. 68 The physiological role of its covalently-bound heme is not completely understood although some observations suggest it may be involved in redox reactions during anaerobic catabolism of carbohydrate during periods of reduced photosynthesis 69 or possibly electron transport on the donor-side of PSII. 70,71 Up-regulation of PsbV in Cu-limited T. oceanica could function as a protective strategy, reducing production of reactive oxygen species by removing excess electrons created by the bottleneck in photosynthetic electron flow.…”

Section: Stress Responsementioning

confidence: 99%

Identification of copper-regulated proteins in an oceanic diatom, Thalassiosira oceanica 1005

Kong

Price

2020

Metallomics

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“…PsbU was first found as a 9 kDa lumenal extrinsic protein in a highly active PS II complex isolated from Phormidium laminosum , which assisted oxygen evolution with PsbO manganese-stabilizing protein ( , ). Another peripheral protein, cytochrome c- 550, was found in Anacystis nidulans and Microcystis aeruginosa ( , ) and was attributed later as an important lumenal extrinsic protein of cyanobacterial PS II (PsbV) ( , ). Both of the corresponding genes ( psbU and psbV ) were then found in all cyanobacterial genomes analyzed except for two strains of Prochlorophytes , Prochlorococcus marinus MED4 and P. marinus SS120 ().…”

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confidence: 99%

PsbU Provides a Stable Architecture for the Oxygen-Evolving System in Cyanobacterial Photosystem II

et al. 2005

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PsbU is a lumenal peripheral protein in the photosystem II (PS II) complex of cyanobacteria and red algae. It is thought that PsbU is replaced functionally by PsbP or PsbQ in plant chloroplasts. After the discovery of PsbP and PsbQ homologues in cyanobacterial PS II [Thornton et al. (2004) Plant Cell 16, 2164-2175], we investigated the function of PsbU using a psbU deletion mutant (DeltaPsbU) of Synechocystis 6803. In contrast to the wild type, DeltaPsbU did not grow when both Ca2+ and Cl- were eliminated from the growth medium. When only Ca2+ was eliminated, DeltaPsbU grew well, whereas when Cl- was eliminated, the growth rate was highly suppressed. Although DeltaPsbU grew normally in the presence of both ions under moderate light, PS II-related disorders were observed as follows. (1) The mutant cells were highly susceptible to photoinhibition. (2) Both the efficiency of light utilization under low irradiance and the chlorophyll-specific maximum rate of oxygen evolution in DeltaPsbU cells were 60% lower than those of the wild type. (3) The decay of the S2 state in DeltaPsbU cells was decelerated. (4) In isolated PS II complexes from DeltaPsbU cells, the amounts of the other three lumenal extrinsic proteins and the electron donation rate were drastically decreased, indicating that the water oxidation system became significantly labile without PsbU. Furthermore, oxygen-evolving activity in DeltaPsbU thylakoid membranes was highly suppressed in the absence of Cl-, and 60% of the activity was restored by NO3- but not by SO4(2-), indicating that PsbU had functions other than stabilizing Cl-. On the basis of these results, we conclude that PsbU is crucial for the stable architecture of the water-splitting system to optimize the efficiency of the oxygen evolution process.

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Low Potential Cytochrome C550 Function in Cyanobacteria and Algae

Cited by 3 publications

References 6 publications

Photosynthetic cytochrome c550

Photosynthetic cytochrome c550

Identification of copper-regulated proteins in an oceanic diatom, Thalassiosira oceanica 1005

PsbU Provides a Stable Architecture for the Oxygen-Evolving System in Cyanobacterial Photosystem II

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