On the function of two vitamin K<sub>1</sub>molecules in the PS I electron acceptor complex

Malkin, Richard

doi:10.1016/0014-5793(86)81046-8

Cited by 71 publications

(33 citation statements)

References 20 publications

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“…A partial loss of PhQ in TX-PS I is consistent with a previous finding that one of the two PhQ molecules can be readily extracted. 20 Though the Chl a/P700 ratio of thylakoid membranes in P. purpureum can vary with the growth irradiance, 21 the Chl a/P700 ratio of thylakoid membranes, 179, agrees well with the previous value, 172, 21 determined at a similar growth irradiance. The Chl a/PS II ratio, 460, deduced from the Chl a/Phe a ratio, 230, was also in line with the Chl a/PS II ratio, 405, determined from the ratio between Chl a and QA, the secondary electron acceptor of PS II.…”

Section: Pigment Composition Of P Purpureumsupporting

confidence: 79%

“…Higher plants and most of the cyanobacteria examined to date contain two molecules of PhQ in PS I, 20,26,27 and there has been no report concerning the participation of MQ-4 in PS I. Since the difference between PhQ and MQ-4 lies only in the number of double bonds on the isoprenoid side chain, the redox potentials of the two naphthoquinones are almost the same within the experimental error.…”

Section: Menaquinone-4 In Ps I Of C Caldariummentioning

confidence: 67%

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Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

2003

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The light reaction of oxygenic photosynthetic organisms proceeds by the cooperation of hundreds of such cofactors as chlorophyll (Chl), quinones, and carotenoids, placed within large pigment-protein complexes, photosystem (PS) I and PS II, in thylakoid membranes. Most Chl molecules function as lightharvesting pigments to funnel the excitation energy to the primary electron donor, P700 in PS I and P680 in PS II (for review, see Ref. 1). In the electron-transfer chains of PS I and PS II, minor Chl a derivatives play crucial roles in light-induced charge separation. 2 PS II contains two molecules of demetallated Chl a, pheophytin (Phe) a, as the primary electron acceptor. 3 We have proposed the existence of one or two molecules of Chl a′, the C13 2 -epimer of Chl a, in PS I through HPLC analysis of pigments.4,5 Recent X-ray crystallography on the PS I trimer of a thermophilic cyanobacterium Synechococcus elongatus revealed that P700 is a heterodimer of Chl a′ and Chl a. However, whether other oxygenic photosynthetic organisms use one Chl a′ molecule in P700 is still unknown. Because Chl a′ has practically the same absorption and fluorescence spectra as Chl a, 7 but shows a different chromatographic behavior, 8 an HPLC analysis of pigment extracts is the sole reliable way for the precise determination of Chl a′ in PS I. For this purpose, the conditions for pigment extraction and HPLC must strictly ensure the molecular integrity of Chl a, since Chl a undergoes several alterations in organic solvents. 9 Recently, we developed such conditions which can deduce the Chl a′/PS I ratio on a single reversed-phase HPLC trace by the simultaneous detection of Chl a′ and phylloquinone (PhQ), the secondary electron acceptor of PS I. 10 Pigment composition analyses of two cyanobacteria, a green alga Chlamydomonas reinhardtii, and spinach, combined with spectrophotometric determination of the Chl a/P700 ratios showed that one Chl a′ molecule exists in the vicinity of P700 in these organisms. 38 The light-harvesting system exhibits a significant variety among oxygenic photosynthetic organisms. 11 Typical cyanobacteria use soluble membrane-extrinsic phycobiliproteins as a light-harvesting system. Green algae and higher plants utilize only membrane-intrinsic Chl a/b complexes, LHC I and LHC II. The light-harvesting systems of red algae are known to be a transitional state from cyanobacteria to green plants, 12,13 and contain both phycobiliprotein and membrane-intrinsic LHC I (containing Chl a alone as the chlorophyllous pigment). 14,15 Hence, the pigment composition of red algae is of much interest to examine the universality of the existence of one Chl a′ molecule in P700.In view of this, we extended the pigment composition analysis to two red algae, a marine alga Porphyridium purpureum employed for many biochemical studies [12][13][14] and an alga living in an extreme environment, Cyanidium caldarium. 16 Experimental Photosynthetic organismsPorphyridium purpureum IAM R-1 was grown in an artificial seawater medium 17 for 7 days at 25...

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Section: Pigment Composition Of P Purpureumsupporting

confidence: 79%

Section: Menaquinone-4 In Ps I Of C Caldariummentioning

confidence: 67%

Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

2003

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“…the native PhQ. Previously, the method used to remove PhQ was to extract lyophilized PS I complexes with solvents, which can remove one (7,8) or both (8 -10) PhQ molecules. Quinone substitution into the A 1 site has been demonstrated for these PS I complexes (11,12).…”

mentioning

confidence: 99%

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Johnson

Zybailov

Jones

et al. 2001

Journal of Biological Chemistry

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Substituted quinones are usually employed as cofactors in electron transport chains, as demonstrated in bacterial reaction centers (1, 2), and in the two photosystems of plants and cyanobacteria (3-5). These quinones comprise a relatively polar ring, which consists of either a benzoquinone (BQ) 1 or a naphthoquinone (NQ) "head group" and a non-polar isoprenoid "tail" of various chain lengths and degrees of saturation. Benzoquinones such as plastoquinone-9 (PQ-9) and ubiquinone-10 function either as fixed or exchangeable electron/proton carriers during photosynthetic and respiratory electron transport. In photosystem II (PS II), PQ-9 functions as a bound one-electron cofactor in the Q A site and as an exchangeable two-electron/ two-proton cofactor in the Q B site. The reduced PQH 2 -9 is displaced from the Q B site, diffuses laterally through the membrane, and becomes oxidized and deprotonated by the cytochrome b 6 f complex. Photosynthetic reaction centers (RCs) of purple bacteria use either ubiquinone-10 (e.g. Rhodobacter sphaeroides) in a similar double role or menaquinone-9 in the Q A site (e.g. Rhodosprillulum viridis). In photosystem I (PS I), phylloquinone (PhQ), a substituted 1,4-NQ with a 20-carbon, largely saturated phytyl tail, functions as a bound one-electron cofactor in the A 1 site. PS I contains two PhQ molecules/P700, but neither of the two quinones functions in a manner equivalent to Q B in the bacterial RC and PS II. Instead, the electron is transferred from the active quinone(s) to soluble ferredoxin via a chain of three bound iron-sulfur centers. Quinones are therefore extremely versatile; they can function as the interface between electron transfer involving organic cofactors and electron transfer involving iron-sulfur clusters (as in PS I), or between pure electron transfer and coupled electron/proton transfer involving a second organic cofactor (as in PS II). Each quinone displays equilibrium binding and redox properties that can be very different for each site of interaction (6), and these properties are conferred largely by the protein environment.To understand the structural determinants that allow quinones to function with a low redox potential in the A 1 site of PS I, we embarked on a project aimed at biological replacement of

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“…(Whether green sulfur bacteria and heliobacteria, which have a PS I-like reaction center, contain a similar bound quinone is still under active investigation.) Two molecules of phylloquinone can be extracted per molecule of P700 from isolated PS I complexes (5-9); however, only one molecule of phylloquinone is considered to participate as an intermediate in electron transfer from A 0 to F X (5,6,10).…”

mentioning

confidence: 99%

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Johnson¹,

Shen²,

Zybailov³

et al. 2000

Journal of Biological Chemistry

132

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Genes encoding enzymes of the biosynthetic pathway leading to phylloquinone, the secondary electron acceptor of photosystem (PS) I, were identified in Synechocystis sp. PCC 6803 by comparison with genes encoding enzymes of the menaquinone biosynthetic pathway in Escherichia coli. Targeted inactivation of the menA and menB genes, which code for phytyl transferase and 1,4-dihydroxy-2-naphthoate synthase, respectively, prevented the synthesis of phylloquinone, thereby confirming the participation of these two gene products in the biosynthetic pathway. The menA and menB mutants grow photoautotrophically under low light conditions (20 E m ؊2 s ؊1 ), with doubling times twice that of the wild type, but they are unable to grow under high light conditions (120 E m ؊2 s ؊1 ). The menA and menB mutants grow photoheterotrophically on media supplemented with glucose under low light conditions, with doubling times similar to that of the wild type, but they are unable to grow under high light conditions unless atrazine is present to inhibit PS II activity. The level of active PS II per cell in the menA and menB mutant strains is identical to that of the wild type, but the level of active PS I is about 50 -60% that of the wild type as assayed by low temperature fluorescence, P700 photoactivity, and electron transfer rates. PS I complexes isolated from the menA and menB mutant strains contain the full complement of polypeptides, show photoreduction of F A and F B at 15 K, and support 82-84% of the wild type rate of electron transfer from cytochrome c 6 to flavodoxin. HPLC analyses show high levels of plastoquinone-9 in PS I complexes from the menA and menB mutants but not from the wild type. We propose that in the absence of phylloquinone, PS I recruits plastoquinone-9 into the A 1 site, where it functions as an efficient cofactor in electron transfer from A 0 to the iron-sulfur clusters.

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On the function of two vitamin K₁molecules in the PS I electron acceptor complex

Cited by 71 publications

References 20 publications

Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

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On the function of two vitamin K1molecules in the PS I electron acceptor complex

Cited by 71 publications

References 20 publications

Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

Reversed-phase HPLC Determination of Chlorophyll a′ and Naphthoquinones in Photosystem I of Red Algae: Existence of Two Menaquinone-4 Molecules in Photosystem I of Cyanidium caldarium

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

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On the function of two vitamin K₁molecules in the PS I electron acceptor complex