Abstract
Psb27 is a highly conserved component of photosystem II. The three-dimensional structure has a well-defined helical core, composed of four helices arranged ill a right-handed up-down-Up-down fold, with a less ordered region of the structure located at the N-terminus. The position of conserved residues oil the surface suggests conserved functional roles for distinct interconnected features encompassing a P-Phi-P loop, a polar patch spanning helices alpha 3 and alpha 4, and the N-terminal sequence.