Irreversibly Binding Photosynthetic Electron Transport Inhibitors II. Halogen-Substituted 1,4-Naphthoquinones and Halogenmethyl-1,4-quinones

Oettmeier, Walter; Dostatni, Ralf; Santel, Hans‐Joachim

doi:10.1515/znc-1987-0608

Cited by 14 publications

(7 citation statements)

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“…Whereas F v /F m is a rather general indicator of PS2 quantum efficiency, t ½ is a much more specific indicator of reactions that inhibit electron flow from the primary to secondary plastoquinone electron acceptors. Because electron transport is known to be inhibited by PAHs both in PS1 (Huang et al 1997c) and PS2 (Oettmeier et al 1987), t ½ should be one of the first fluorescence induction parameters to respond to anthracene toxicity. Our work supports that view; near complete inhibition of t ½ values was apparent after 1 h of anthracene exposure under SSR.…”

Section: Discussionmentioning

confidence: 99%

“…One major issue to be resolved is the length of time that plants need to be exposed to contaminants before meaningful fluorescence data can be obtained and whether such data are predictive of inhibition of endpoints at higher levels of ecological organization (Gensemer et al 1996). Given the rapid responses of biochemical processes in photosynthesis to environmental contaminants (Oettmeier et al 1987;Huang et al 1997c), Chl a fluorescence parameters potentially could respond within seconds to a chemical insult. Huang et al (1997a) demonstrated that Chl a fluorescence induction in L. gibba was inhibited after only 4 h of exposure to anthracene under SSR.…”

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confidence: 99%

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Using chlorophyll a fluorescence to detect the onset of anthracene photoinduced toxicity in Lemna gibba, and the mitigating effects of a commercial humic acid

Gensemer

Dixon

Greenberg

1999

Limnology & Oceanography

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The influence of a commercial humic acid (Aldrich; AHA) on the development of anthracene photoinduced toxicity to the duckweed Lemna gibba was examined using both room-and low-temperature (77ЊK) chlorophyll fluorescence assays. Plants were exposed to 2 mg liter Ϫ1 anthracene both with and without 6.2 mg liter Ϫ1 of AHA and grown under either visible light or simulated solar radiation that mimics the natural abundance of UV radiation. Exposure periods ranged from 1 to 48 h to examine temporal changes in chlorophyll degradation and chlorophyll a fluorescence induction in response to these light and HA treatments. The onset of anthracene photoinduced toxicity followed a definite sequence; chlorophyll a fluorescence induction parameters (F v /F m , and t ½ ) responded earliest to anthracene exposure, with observable chlorophyll degradation requiring up to 24 to 48 h. Of these, t ½ was the most sensitive, with significant inhibition apparent within 1 h of exposure. Throughout the entire 48-h exposure, 6.2 mg liter Ϫ1 AHA ameliorated the photoinduced toxicity of anthracene, in terms of both chlorophyll degradation and F v / F m inhibition. In contrast, AHA delayed the complete inhibition of t ½ by only 1 to 24 h rather than permanently protecting the plants from anthracene damage to PS2. This suggests that AHA may slow, but not prevent, the entrance of either intact anthracene or its photooxidized byproducts under these exposure conditions.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Using chlorophyll a fluorescence to detect the onset of anthracene photoinduced toxicity in Lemna gibba, and the mitigating effects of a commercial humic acid

Gensemer

Dixon

Greenberg

1999

Limnology & Oceanography

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“…Thus, NQ derivatives that are analogs or direct products of the naphthoate synthase enzyme appear to slow the growth of the wild-type cells. All three cyanobacterial strains ceased to grow shortly after addition of 5-OH-1,4-NQ, 2-CH 3 -5-OH-1,4-NQ, and 2,3-diCl-1,4-NQ, which are known herbicides (22)(23)(24).…”

Section: Isolation Of a High Light Tolerantmentioning

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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“…For instance, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), a plastoquinone analog, is a classical inhibitor of the cytochrome b 6 /f complex in the photosynthetic electron transport chain (Izawa, 1977;Trebst, 1980). But also herbicide-like actions on the Q B site of PSII by 1,4 benzoquinones, -naphthoquinones and anthraquinones have been described (Oettmeier et al, 1987(Oettmeier et al, , 1988. However, at relatively high-concentrations (10-20 lM), DBMIB acts as a PSII electron acceptor (Izawa et al, 1973).…”

Section: Discussionmentioning

confidence: 99%

Selected coccal green algae are not affected by the humic substance Huminfeed® in term of growth or photosynthetic performance

et al. 2012

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Humic substances (HSs) have been shown to influence growth, photophysiology, and redox homeostasis in phototrophs. However, many ecological studies deliver controversial results indicating inhibitory or stimulating effects depending on the kind of phototrophic organism or type of HSs applied. Here we analyzed the effect of Huminfeed Ò (HF), a preparation from leonardite associated with lignite deposits, on growth and photosynthetic performance of three different coccal green algae. Concentrations of HF in the range of 2-20 mg l -1 dissolved organic carbon (DOC) did neither affect the growth rate nor the light-adapted photosynthetic electron transport. Even photoinhibitory light intensities of 1,600 lmol photons m -2 s -1 , representing the tenfold of growth light intensity, did not result in a decline of the maximal photosynthetic rate in HF-treated algae. In HF-grown algae, a very subtle decrease by about 10% could be observed in thermoluminescent light emission, a sensitive method to detect changes in photosystem II (PSII) chemistry. However, thermoluminescence (TL) represents only 3% of the light-induced charge separated states in PSII. Hence, rather small changes will not have significant effects on overall photosynthetic performance and growth. Therefore, the physiological effect of HSs on freshwater phototrophs has to be revisited.

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Irreversibly Binding Photosynthetic Electron Transport Inhibitors II. Halogen-Substituted 1,4-Naphthoquinones and Halogenmethyl-1,4-quinones

Cited by 14 publications

References 0 publications

Using chlorophyll a fluorescence to detect the onset of anthracene photoinduced toxicity in Lemna gibba, and the mitigating effects of a commercial humic acid

Using chlorophyll a fluorescence to detect the onset of anthracene photoinduced toxicity in Lemna gibba, and the mitigating effects of a commercial humic acid

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

Selected coccal green algae are not affected by the humic substance Huminfeed® in term of growth or photosynthetic performance

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