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Biochimica et Biophysics Acta, 1058(1991) 289-296 01991Elsevier Science Publishers B.V. 0005-2728/91/$03.50
 

Summary: Biochimica et Biophysics Acta, 1058(1991) 289-296
01991Elsevier Science Publishers B.V. 0005-2728/91/$03.50
ADONIS 000527289100162A
BBABIO 43415
Light-dependentphosphorylation of Photosystem I1 polypeptides
maintains electron transport at high light intensity: separation
from effects of phosphorylation of LHC-I1
Michael A. Harrison and John F. Alien *
Department of Pure andApplied Biology, Universityof Leeds, Leeds (U.K.)
(Received 5 November 1990)
Key words: Photosynthesis; Protein phosphorylation; Protein phosphatase; Photosystem 11; Electron transport; Photoinhibition
Phosphorylation of chloroplast thylakoid membrane proteins, including LHC-I1 and PS I1 polypeptides D,, D,, CP43
and the psbH gene product, occurs under plastoquinone-reducing conditions. Dephosphorylation of LHC-I1 and PS I1
phosphoproteins proceeds under plastoquinone-oxidizing conditions, but with differing kinetics. This study shows that
phosphorylationsites of PS I1polypeptidesare substrates for exogenous alkaline phosphatase activity, whereas those of
LHC-I1 are not. By combined use of exogenous and endogenous phosphatase activities four types of thylakoid
membrane are generated, with (i) both LHC-I1 and PS I1 polypeptides phosphorylated, (ii) only PS I1 polypeptides
phosphorylated, (iii) only LHC-I1 phosphorylated and (iv) neither class of polypeptide phosphorylated. Examination of
PS I1 electron transport in each membrane type shows that a mechanism involving phosphorylation of PS I1
polypeptides specifically is required for PS I1 function at high light intensity. Phosphorylation of LHC-I1 results in an

  

Source: Allen, John F. - School of Biological and Chemical Sciences, Queen Mary, University of London

 

Collections: Renewable Energy; Biology and Medicine