In vitro assembly of a beta(2) cytochrome b(559)-like complex from the chemically synthesised beta-subunit encoded by the Synechocystis sp 6803 psbF gene

The alpha- and beta-subunits of cytochrome b(559) encoded by the psbE and p sbF gene, respectively, are essential components of photosystem II. The exa ct structure of this cytochrome is not yet known. The beta-subunit of the S ynechocystis sp, 6803 cytochrome b(559) complex was synthesised by means of solid-phase peptide synthesis. Under reducing conditions, two beta-peptide molecules could be assembled specifically with one haem to form a beta(2) cytochrome b(559)-like complex, The spectral properties and the midpoint re dox potential (48 +/- 5 mV) of the in vitro assembled beta(2) cytochrome ar e nearly identical to those of the low potential form of the native cytochr ome b(559). (C) 1999 Federation of European Biochemical Societies.