A Contact Site between the Two Reaction Center Polypeptides of Photosystem II Is Involved in Photoinhibition

Abstract

A new contact site between the two reaction center polypeptides D1 and D2 of photosystem II close to arg238 and arg234 respectively is proposed. The amino acid sequences involved are between the 4th transmembrane and a connecting parallel helix. The sequence includes a trypsin sensitive site in both polypeptides, the likely cleavage site in the rapid turnover of the D 1 polypeptide and part of the herbicide binding site. The contact site is oriented towards both quinone binding sites QA and QB. A folding of the backbone of the amino acid sequences involved is proposed. © 1991, Walter de Gruyter. All rights reserved.