Subproject 2

Auxiliary factors for chlorophyll biosynthesis and connection to the assembly of chlorophyll-binding proteins

Project leader: Prof. Dr. Bernhard Grimm

Chlorophyll biosynthesis provides the essential pigments for photosynthesis in photoautotrophic organisms. While genes encoding enzymes of the pathway and the metabolic reactions have been elucidated, studies on posttranslational modifications and the spatio-temporal organization of the pathway as well as its functional coupling to the assembly of chlorophyll into photosynthetic proteins are the next steps in the analyses of the complex chlorophyll metabolism. The objective of this subproject is the elucidation of the functional and structural role of two auxiliary factors for the organization of the late steps of chlorophyll biosynthesis and the subsequent link to the assembly of chlorophyll-binding proteins: LIL3 (light-harvesting-like protein 3) and Pitt-homologous plastid-localized tetratricopeptide-repeat proteins (cpTPRs). Their interaction partners in chlorophyll biosynthesis are aimed to be identified and verified in wild-type and mutant plants by means of protein chromatography, mass spectrometry and electron microscopy. In cooperation with partners of the Research Unit it is intended to validate in a cross-species approach the functional specificity of homologous LIL3 and cpTPRs form other model species. Thereby, these physiological and biochemical analyses contribute to the central objective of this Research Unit to explore assembly factors required for the biogenesis of thylakoid membranes.