Identification of a novel GluTR-binding protein
Judith Schmied, Zhiwei Hou, Boris Hedtke
The fine-tuned control of GluTR is dependent on GBP which binds at the N-terminal HBD of GluTR. Both proteins, GluTR and GBP, can be found in stroma and thylakoid fractions of plastids. The gbp knockout mutants show a stronger reduction of heme content than of chlorophyll content. Depletion of GBP results in accelerated degradation of GluTR during prolonged dark periods. Moreover, co-overexpression of GluTR and GBP in N. tabacum causes a severe necrotic phenotype, whereas sole overexpression of either GluTR or GBP does affect ALA and tetrapyrrole biosynthesis only.
Necrotic phenotype of N. tabacum leaf upon induced co-overexpression of AtGluTR and AtGBP.
Continuous interaction studies and analysis of the spatial organization of both proteins within plastids will be performed to obtain a deeper insight into the contribution of GBP to GluTR stability and the control of the rate-limiting ALA biosynthesis.