Sulfhydryl reagents and energy-linked reactions in monocot thylakoids

Monofunctional maleimides have been used to covalently modify the coupling factor protein of monocot thylakoid membranes. As with dicot thylakoids, incubation of the monocot thylakoids with maleimides in the light but not in the dark results in inhibition of both ATP synthesis and hydrolysis, In the...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1990-07, Vol.93 (3), p.1005-1010
Main Authors: Cohen, W.S. (University of Kentucky, Lexington, KY), Baxter, D.R
Format: Article
Language:English
Subjects:
Adenosine triphosphatases
ADENOSINE TRIPHOSPHATE
ADENOSINTRIFOSFATO
Biological and medical sciences
BIOSINTESIS
BIOSYNTHESE
Cell structures and functions
Chloroplast, photosynthetic membrane and photosynthesis
Chloroplasts
COMPOSE ORGANOSOUFRE
COMPUESTO ORGANICO DEL AZUFRE
Corn
coupling factor
DIGITARIA
energy transduction
FOSFORILACION
FOTOSINTESIS
Fundamental and applied biological sciences. Psychology
Grinding
HIDROLASAS
HIDROLISIS
HORDEUM VULGARE
HYDROLASE
HYDROLYSE
Membranes and Bioenergetics
Mesophyll
Molecular and cellular biology
PHOSPHORYLATION
Photophosphorylation
PHOTOSYNTHESE
PISUM SATIVUM
PLASTE
PLASTIDIOS
PROTEINAS
PROTEINE
Protons
Reagents
Spinach
SPINACIA OLERACEA
thylakoid membranes
Thylakoids
ZEA MAYS
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Description
Summary:Monofunctional maleimides have been used to covalently modify the coupling factor protein of monocot thylakoid membranes. As with dicot thylakoids, incubation of the monocot thylakoids with maleimides in the light but not in the dark results in inhibition of both ATP synthesis and hydrolysis, In the dark, sites on the gamma epsilon subunits of maize Zea mays coupling factor 1 are modified after incubation of maize mesophyll thylakoids with the fluorescent maleimide N-(anilinonaphthyl-4) maleimide. A light accessible site localized solely to the gamma subunit has also been demonstrated. In contrast to the case with dicot thylakoids (spinach [Spinacia oleracea] and pea [Pisum sativum]) treatment of monocot thylakoids (maize, barley [Hordeum vulgare], crabgrass [Digitaria sanguinalis]) with bifunctional maleimides or thiol oxidants in the light does not result in functional uncoupling, i.e. the bifunctional reagents act more like energy transfer inhibitors. The lack of functional uncoupling could be due either to a failure of the reagents to cross-link key sulfhydryl residues in the gamma subunit or to the continued ability of the gamma subunit to gate proton movements through the chloroplast coupling factor complex even though its conformation has been altered by sulfhydryl reagents
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.93.3.1005