The Binding of Xanthophylls to the Bulk Light-harvesting Complex of Photosystem II of Higher Plants

The pigment composition of the light-harvesting complexes (LHCs) of higher plants is highly conserved. The bulk complex (LHCIIb) binds three xanthophyll molecules in combination with chlorophyll (Chl) a and b. The structural requirements for binding xanthophylls to LHCIIb have been examined using an in vitro reconstitution procedure. Reassembly of the monomeric recombinant LHCIIb was performed using a wide range of native and nonnative xanthophylls, and a specific requirement for the presence of a hydroxy group at C-3 on a single β-end group was identified. The presence of additional substituents (e.g.at C-4) did not interfere with xanthophyll binding, but they could not, on their own, supp…