Functional characterization of a novel plastidal thioredoxin and its putative target proteins

• Applicant: Professor Dr. Frederik Börnke
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2010 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 186875881

Thioredoxins (TRX) are small ubiquitous proteins with a redox-active disulfide bridge responsible for the regulation of a broad range of target proteins. We have identified TRX z that represents a novel plastidial TRX essential for autotrophic growth. The Arabidopsis trx z T-DNA knockout mutant displays a specific decrease in the expression of genes that depend on a multi-subunit plastid-encoded RNA polymerase (PEP). We could identify two fructokinase-like proteins (FLP1 and FLP2), members of the pfkB-carbohydrate kinase family, as potential TRX z target proteins. Virus-induced gene silencing of FLPs in N. benthamiana led to a similar repression of PEP-dependent gene transcription as the suppression of TRX z function in Arabidopsis. We hypothesize that TRX z is required for chloroplast transcription possibly serving as a mediator of redox-(light-) and, via its target proteins, other stimuli regulating transcriptional activity in chloroplasts in response to fluctuating environmental conditions. To fully understand the function of TRX z we are planning to use a combination of transgenic, molecular and biochemical approaches. We propose that this will lead to the identification of novel redox regulated processes and thus new insights into redox regulation in plants.

• DFG Programme: Research Grants