The site and mechanism of duroquinol oxidation by the cytochrome b6-f complex in Synechococcus sp.

Nanba, Masaru; Katoh, Sakae

doi:10.1016/0005-2728(86)90085-x

Cited by 19 publications

(8 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5). This reagent is an efficient electron donor to the cytochrome b6fcomplex (Nanba and Katoh 1986). It would therefore enhance PSI turnover by providing an additional source of electrons to the donor side of PSI and inhibit PS II turnover by competing with plastoquinone for oxidising equivalents at the cytochrome bo r complex.…”

Section: Discussionmentioning

confidence: 99%

“…Duroquinol is a lipid-soluble reducing agent whose presence causes the plastoquinone pool to become more reduced. However, the efficiency of electron transfer from duroquinol to plastoquinone appears to be rather low, and it seems likely that duroquinol acts principally as a direct electron donor to a quinone binding site on the cytochrome brfcomplex [Nanba and Katoh, 1986]. The ability of duroquinol to donate electrons to the cytochrome b6f complex in intact cyanobacterial cells has been well-established (Nanba and Katch 1986).…”

Section: Effect Of Dbmib On Light-statementioning

confidence: 99%

“…Methyl viologen can act as a PSI electron acceptor in intact cyanobacterial cells (Chua 1971, Nanba andKatoh 1986). Figure 7 shows that methyl viologen has no significant effect on excitation energy distribution in dark-adapted cells.…”

Section: Effect Of Methyl Viologen On Light-statementioning

confidence: 99%

See 2 more Smart Citations

State 1-State 2 transitions in the cyanobacterium Synechococcus 6301 are controlled by the redox state of electron carriers between Photosystems I and II

1990

View full text Add to dashboard Cite

The mechanism by which state 1-state 2 transitions in the cyanobacterium Synechococcus 6301 are controlled was investigated by examining the effects of a variety of chemical and illumination treatments which modify the redox state of the plastoquinone pool. The extent to which these treatments modify excitation energy distribution was determined by 77K fluorescence emission spectroscopy. It was found that treatment which lead to the oxidation of the plastoquinone pool induce a shift towards state 1 whereas treatments which lead to the reduction of the plastoquinone pool induce a shift towards state 2. We therefore propose that state transitions in cyanobacteria are triggered by changes in the redox state of plastoquinone or a closely associated electron carrier. Alternative proposals have included control by the extent of cyclic electron transport around PS I and control by localised electrochemical gradients around PS I and PS II. Neither of these proposals is consistent with the results reported here.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Effect Of Dbmib On Light-statementioning

confidence: 99%

See 1 more Smart Citation

State 1-State 2 transitions in the cyanobacterium Synechococcus 6301 are controlled by the redox state of electron carriers between Photosystems I and II

1990

View full text Add to dashboard Cite

show abstract

“…Our assumption that DPIP-mediated reaction reflects transport through Cyt f is based on previous reports (11,21,25) that ascorbate-reduced DPIP donates its electrons very closely to or directly to Cyt f Direct membrane damage at Cyt f/b6 results from heat, which changes the site of the DPIP electron donation to the Cyt f/b6 complex in pea (Pisum sativum L.) chloroplasts (25). A conformational change exposes new DPIP acceptor sites and increases DPIP-mediated activity after brief incubation at high temperatures.…”

Section: Discussionmentioning

confidence: 99%

Photosynthetic Decline from High Temperature Stress during Maturation of Wheat

Tsai¹,

Guikema²,

Paulsen³

1990

Plant Physiol.

138

View full text Add to dashboard Cite

Photosynthetic capacity decreases rapidly when temperate species are exposed to heat stress during reproductive development. We investigated whether injury in wheat (Triticum aestivum L.) resulted from general acceleration of senescence processes or specific heat-induced lesions. In situ photosynthetic capacity of leaf discs and thylakoid reactions were measured using flag leaf tissue from two cultivars maintained at 20 and 350C during maturation. Photosynthetic rates of leaf discs decreased faster at 35 than at 200C and were more photolabile in cv Len than in cv Waverly at high temperature. Patterns of thylakoid breakdown also differed in the two wheat genotypes at 20°C: intersystem electron transport and photosystem 11 activity decreased linearly during postanthesis development in Len wheat, whereas coupling of photophosphorylation to electron transport declined late during senescence in Waverly wheat. Heat stress induced early loss of intersystem electron transport followed sequentially by decreased silicomolybdic acid, + 3-(3,4-dichlorophenyl)-1-dimethylurea-mediated photosystem 11 activity and 2,5-dichloro-p-benzoquinone-mediated photosystem 11 activity in Len. Stress accelerated the uncoupling process, but loss of intersystem electron transport and photosystem 11 activities was slower in Waverly than in Len

show abstract

“…Table II shows that DBMIB, DNP-INT, HQNO and CCCP do not considerably influence the electron transfer from H,O to SiMo (involving photosystem II), nor that from reduced TMPD to methylviologen (involving photosystem I). Electron transfer from duroquinol reducing Qz [15,17] to methylviologen with participation of photosystem I was almost completely inhibited by DBMIB and DNP-INT, but only slightly sensitive to CCCP. Electron transfer from H,O to FeCy was over 50% decelerated by DBMIB and DNP-INT (thus indicating that FeCy is reducible both by photosystems II and I) and drastically inhibited by HQNO and CCCP.…”

Section: Resultsmentioning

confidence: 92%

Interaction of carbonyl cyanide m‐chlorophenylhydrazone with the photosystem II acceptor side

Самуилов

Barsky

1993

FEBS Letters

View full text Add to dashboard Cite

We show that CCCP, known as an uncoupler of photophosphorylation and an ADRY agent, inhibits FeCy photoreduction and coupled 0, evolution by isolated chloroplasts equally (I,, -2 PM), but is practically without effect on the O2 evolution coupled with SiMo reduction within the 0.2-10pM concentration range. CCCP has no effect on the nanosecond chlorophyll fluorescence in chloroplasts incubated at low light intensity, but decreases it at high light intensity. The electron transfer from reduced TMPD or duroquinol to methylviologen IS resistant to CCCP. The efficiency of the CCCP inhibitory action on the FeCy photoreduction depends on the rate of electron flow, which is controlled by the light intensity. The data obtained show that CCCP is oxidized by the photosystem II donor side and is reduced by Qr. competing for electrons with FeCy and the cytochrome blfcomplex.

show abstract

The site and mechanism of duroquinol oxidation by the cytochrome b6-f complex in Synechococcus sp.

Cited by 19 publications

References 27 publications

State 1-State 2 transitions in the cyanobacterium Synechococcus 6301 are controlled by the redox state of electron carriers between Photosystems I and II

State 1-State 2 transitions in the cyanobacterium Synechococcus 6301 are controlled by the redox state of electron carriers between Photosystems I and II

Photosynthetic Decline from High Temperature Stress during Maturation of Wheat

Interaction of carbonyl cyanide m‐chlorophenylhydrazone with the photosystem II acceptor side

Contact Info

Product

Resources

About