ASSOCIATION OF PROTOCHLOROPHYLLIDE WITH THE PUFQ PROTEIN OF RHODOBACTER-CAPSULATUS

The PufQ protein, prepared by the recombinant expression of the pufQ g ene of Rhodobacter capsulatus, has been reconstituted into liposomes i n the presence of the bacteriochlorophyll precursor, protochlorophylli de. The liposomes were separated from liposomes free of the PufQ prote in by sucrose density gradient ultracentrifugation and analyzed for th eir content of protochlorophyllide, protein, and phospholipid. The res ults indicated a 3.5 times higher level of association of protochlorop hyllide with the PufQ protein-containing liposomes than with liposomes containing either the hydrophobic protein, apolipoprotein A-I, or the water-soluble maltose-binding protein. Only the association of the pr otochlorophyllide with the PufQ protein corresponded to a small but re producible shift in its fluorescence emission maximum to a lower wavel ength, consistent with a change in its environment. (C) 1994 Academic Press, Inc.