The Topology of the Plastoquinone and Herbicide Binding Peptides of Photosystem II in the Thylakoid Membrane

Abstract

The 32 kDa herbicide and QBbinding peptide (D-1 protein) and its homologous 34 kDa peptide (D-2 protein) are integral membrane subunits of photosystem II. A model for their folding through the thylakoid membrane in five transmembrane α-helices is proposed from the comparison of amino acid sequence and hydropathy index plot homologies with subunits of the bacterial system. Following recent data on the X-ray structure of a bacterial photosystem the binding niche for QBis interpreted on the basis of the amino acid changes found in the 32 kDa peptide in herbicide tolerant higher plants and algae. © 1986, Verlag der Zeitschrift für Naturforschung. All rights reserved.