Fragmentation and separation of the thylakoid membrane effect of light-induced protein phosphorylation on domain composition

Abstract

The thylakoid membrane consists of three main compartments, the stroma lamellae, the central appressed region of grana and the peripheral grana margins. These three domains can be separated from each other by fragmentation and aqueous two-phase partitioning. Upon phosphorylation the light-harvesting chlorophyll a/b binding complex II (LHC II) dissociates away from photosystem II in grana and migrates into the stroma lamellae. Dynamic processes, such as lateral migration of LHC II, can be examined by analysing corresponding fragments from phosphorylated and non-phosphorylated thylakoids. Our results show that we can detect not only the well studied lateral migration of phosphorylated LHC II from grana to stroma lamellae, but also migration within the grana disc, from the core of grana to the margins of grana. Furthermore, we show that the grana margin vesicles and the stroma lamellae vesicles are heterogeneous populations that can be fractionated further by counter-current distribution.