THE TRANSIT SEQUENCE OF A CHLOROPLAST PRECURSOR PROTEIN REORIENTS THE LIPIDS IN MONOGALACTOSYL DIGLYCERIDE CONTAINING BILAYERS

The interaction of the chloroplast precursor protein of ferredoxin with mixed model membranes composed of H-2 chain labeled monogalactosyl diacylglycerol and phosphatidylcholine was studied by H-2 and P-31 NMR. The bilayers were found to have special chain packing properties which most likely are the result of a specific arrangement of head groups at the interface. The precursor and not the corresponding apoprotein induced a bilayer-->isotropic transition in lipid organization as a result of the transit sequence-lipid interaction. The implications of these observations for proteins import into chloroplasts are indicated.