Project-Group: Dr. Heike Holländer-Czytko
In metal homeostasis of plants a lot of genes have been detected whose expression is up- or downregulated on metal deficiency or metal surplus. Among them are genes encoding HMA4-ATPase (Heavy metal ATPase4), a transporter of zinc into the xylem and nicotianamine synthases, proteins in the biosynthesis of the chelator nicotianamine from S-adenosyl-methionine. In our group we have cloned the cDNAs of those genes from the model plant A. thaliana and the metal hyperaccumulator plant A. halleri with the aim to express the corresponding proteins and do characterization on protein level. Also, we are cloning and expressing certain domains of the proteins for antibody production.
In addition we transform Arabidopsis halleri from roots and leaves (cocultivation with Agrobacterium tumefaciens) with constructs of interest and maintain a large collection of sterile transgenic A. halleri lines that have been created over the years in the lab. In these transgenic plants genes related to metalhomeostasis
have been silenced, overexpressed (with or without induction) or promoter-reporter gene fusions are expressed to study regulation and do localization studies.
Fig. 1: Regeneration of A. halleri after transformation with A. tumefaciens
Furthermore we are interested in oxylipin regulated proteins and have cloned several transaminases (TAT) and cystin lyases (CL) from A. thaliana. These enzymes are involved in tocopherol biosynthesis and possibly in the methionine cycle and iron/sulfur protein biogenesis. We have characterized them on protein level and looked into their expression on protein and transcriptional level after induction with oxylipins and in stress situations. Also, we showed their subcellular localization with eGFP-fused proteins.
Fig. 2: Localization of eGFP, TAT-eGFP and Cl-eGFP in tobacco cells after transient transformation (particle gun)
