Crystallization of Intact and Subunit L-Deficient Monomers from Synechocystis PCC 6803 Photosystem I

Abstract

Abstract Photosystem I monomers from wildtype cells of Synechocystis PCC 6803 and from a mu­ tant deficient in the psaL gene were crystallized. PsaL encodes for the hydrophobic subunit L, which has been proposed to constitute the trimerization domain in the PS I trimer. The absence of subunit L facilitated crystallization of the PS I monomer. The unit cell dimensions and the space group for the crystals from this preparation could be determined to be a = b = 132 Å , c -525 Å, α = β = 90°, y = 120°, the space group is P6 1 or P6 5 . The results show the potential of using specifically designed deletion mutants of an integral membrane protein for the systematic improvement of crystal structure data.