Auxiliary factors for chlorophyll biosynthesis and their potential contribution to the assembly of chlorophyll into chlorophyll-binding proteins

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Chlorophyll biosynthesis provides the essential pigments for photosynthesis in photoautotrophic organisms. While almost all enzymatic steps of have been elucidated, the spatio-temporal organization of the pathway as well as its functional coupling to the assembly of chlorophyll into photosynthetic proteins are still open questions. In continuation, the objective of this subproject is (i) the in-depth elucidation of the functional and structural roles of LIL3 (light-harvesting-like protein 3) and Pitt-homologous plastid-localized tetratricopeptide-repeat proteins (cpTPRs) for the organization of the late steps of chlorophyll biosynthesis and (ii) the examination of the functional roles of additional auxiliary factors which are required either for chlorophyll biosynthesis or the subsequent link to the assembly of chlorophyll-binding proteins, such as OHP (one-helix-protein), YCF54 (hypothetical chloroplast open reading frame 54) and CPL (Chaperone-like protein of POR1 (CPP1)-like protein). Their interaction partners are aimed to be newly identified or confirmed in wild-type and mutant plants by means of advanced biochemical methods, such as protein affinity chromatography and mass spectrometry, or fluorescence and electron microscopy (in part in cooperation with partners of the Research Unit). Thereby, these physiological and biochemical analyses contribute to the central objectives of the Research Unit to validate assembly factors required for the stepwise assembly of photosynthetically active protein complexes in thylakoid membranes.