ISOLATION OF THYLAKOID MEMBRANE-VESICLES OF CHLAMYDOMONAS-REINHARDII CHLOROPLASTS THAT ARE ABLE TO INTEGRATE AND IMPORT IN-VITRO SYNTHESIZED PRECURSOR PROTEINS

Once imported into the stroma, nuclear encoded proteins of the chlorop last have to be routed to their final compartment, e,g, the thylakoid membranes. Four different pathways have been reported for the transloc ation of precursor proteins across and for the integration of mature p roteins into the thylakoid membranes in higher plants, To study the so rting of precursor proteins in chloroplasts of higher plants the gener ation of an in vitro system using isolated intact thylakoid membrane v esicles was of major importance. Here we report the isolation of intac t thylakoid membrane vesicles of the green algae Chlamydomonas reinhar dii for the generation of a similar algal system. Further we show succ essful transport of several Chlamydomonas precursor proteins into isol ated thylakoids: Lumenal precursors were translocated into the vesicle s resulting in the accumulation of their mature, thermolysin-insensiti ve forms and thylakoid membrane proteins were specifically integrated into isolated Chlamydomonas thylakoid membranes. (C) 1997 Academic Pre ss.