Claus Schwechheimer

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The COP9 signalosome is an evolutionary conserved multiprotein complex of unknown function that acts as a negative regulator of photomorphogenic seedling development in Arabidopsis. Here, we show that plants with reduced COP9 signalosome levels had decreased auxin response similar to loss-of-function mutants of the E3 ubiquitin ligase SCFTIR1. Furthermore,(More)
Gibberellic acid (GA) promotes seed germination, elongation growth, and flowering time in plants. GA responses are repressed by DELLA proteins, which contain an N-terminal DELLA domain essential for GA-dependent proteasomal degradation of DELLA repressors. Mutations of or within the DELLA domain of DELLA repressors have been described for species including(More)
The phytohormone gibberellin (GA) regulates various developmental processes in plants such as germination, greening, elongation growth, and flowering time. DELLA proteins, which are degraded in response to GA, repress GA signaling by inhibitory interactions with PHYTOCHROME-INTERACTING FACTOR (PIF) family transcription factors. How GA signaling is(More)
Plants integrate different regulatory signals to control their growth and development. Although a number of physiological observations suggest that there is crosstalk between the phytohormone gibberellin (GA) and auxin, as well as with auxin transport, the molecular basis for this hormonal crosstalk remains largely unexplained. Here, we show that auxin(More)
The COP9 signalosome is an evolutionarily conserved multiprotein complex that was first identified as an essential complex that represses light-regulated development in Arabidopsis. The COP9 signalosome has similarity to the lid of the 19S regulatory particle of the 26S proteasome and has recently been shown to interact with SCF-type E3 ubiquitin ligases.(More)
The COP9 signalosome (CSN) is a multiprotein complex of the ubiquitin-proteasome pathway. CSN is typically composed of eight subunits, each of which is related to one of the eight subunits that form the lid of the 26S proteasome regulatory particle. CSN was first identified in Arabidopsis where it is required for the repression of photomorphogenic seedling(More)
The COP9 signalosome (CSN) was originally identified based on the constitutively photomorphogenic/de-etiolated/fusca (cop/det/fus) mutants from Arabidopsis thaliana. CSN is evolutionary conserved, and its subunit 5 (CSN5) mediates the deconjugation of NEDD8 from the cullin subunit of E3 ubiquitin ligases (deneddylation). Here, we report on Arabidopsis(More)
The development and morphology of vascular plants is critically determined by synthesis and proper distribution of the phytohormone auxin. The directed cell-to-cell distribution of auxin is achieved through a system of auxin influx and efflux transporters. PIN-FORMED (PIN) proteins are proposed auxin efflux transporters, and auxin fluxes can seemingly be(More)
The aim of this work was to design strong transcriptional activators that can be used to regulate plant gene expression. The contribution of different components in a transcription factor and target gene system was assayed by measuring transcriptional activation. Each component was optimised to achieve maximal reporter gene expression in transient(More)
The COP9 signalosome (CSN) is required for the full activity of cullin-RING E3 ubiquitin ligases (CRLs) in eukaryotes. CSN exerts its function on CRLs by removing the ubiquitin-related NEDD8 conjugate from the cullin subunit of CRLs. CSN seems, thereby, to control CRL disassembly or CRL subunit stability. In Arabidopsis thaliana, loss of CSN function leads(More)