Subproject 6

Identification and functional analysis of photosystem assembly factors at thylakoid centers in Chlamydomonas reinhardtii

Project leader: Prof. Dr. Michael Schroda

Recent work suggested a role of the vesicle inducing protein in plastids (VIPP1) in photosystem biogenesis. Moreover, the plastidic HSP70/HSP90 chaperone machinery was shown to mediate the dynamic (dis)assembly of VIPP1 supercomplexes. The latter are likely to play a structural role in thylakoid centers from which thylakoid membranes emerge and at which the biogenesis at least of photosystem II is considered to occur. Affecting VIPP1 function directly or indirectly by affecting components of the chaperone machinery in Chlamydomonas leads to the accumulation of aggregates at sites corresponding to thylakoid centers. These aggregates are likely to contain photosystem assembly intermediates. In this project we wish to use these findings as an entry point to characterize factors involved in photosystem biogenesis at thylakoid centers. We wish to (i) identify these factors using biochemical and forward genetics approaches; (ii) temporally and spatially characterize their roles during thylakoid biogenesis; (iii) gain insights to their functional evolution.