Humboldt-Universität zu Berlin - AG Pflanzenphysiologie

Interaction of GluTR with the negative regulator FLU

Zhiwei Hou, Judith Schmied, Boris Hedtke


The tetratricopeptide-repeat (TPR) containing FLUORESCENT IN BLUE LIGHT (FLU) has been reported to inactivate GluTR and down-regulate ALA synthesis during darkness by binding to the C-terminus of GluTR. We currently aim to investigate in planta the role of the C-terminal end of GluTR for FLU-binding and to prove the physiological and catalytic effects of truncated GluTR without the FLU-binding domain. Moreover, it is intended to unravel the degree of membrane-bound GluTR during photoperiodic growth which is mediated by FLU and GBP. It is hypothesized that the ratio of soluble and membrane-associated GluTR decides about the rate of ALA synthesis and GluTR stability. This substantiates the idea of a regulatory complex determining GluTR activity. In addition, FLU function is examined during light exposure in the flu mutants and in FLU-overexpressing Arabidopsis lines. It is hypothesized that FLU acts on ALA synthesis during photoperiodic growth to fine-tune GluTR activity.

GluTR and FLU

Zhiwei Hou, unpublished results


The distribution of proteins involved in control and catalysis of ALA biosynthesis in the plastidic stroma and membrane fraction of seedlings grown under continuous light. The amount of soluble and membrane-associated GluTR differs remarkably in flu knock-out mutants in comparison to control. This varying distribution determines the rate of ALA synthesis and the accessibility to proteolytic degradation.