OWL1 - a molecular tool to dissect the phytochrome A-dependent Very Low Fluence Response (VLFR)
Final Report Abstract
This project yielded interesting findings to clarify the very fluence-dependent phytochromeA signal transduction: (1) OWL1 is probably a central factor in the very low fluence response. (2) Due to the presence of a J-domain this protein could recruit proteins to the HSP70/HSP90 complex for modifications. Interaction partners such as HSP70-1 and HSP81.2 strongly support this notion. (3) Proteins that are recruited by OWL1 could be transcription factor. Loss-of-function mutant analysis showed that several of the interacting transcription factors have a role in phytochrome signaling. (4) The VLFR could influence other signaling pathways, such as the phyB-dependent EOD FR response. Some factors that have been isolated as putative interactors have a role in phyA-dependent HIR (HFR1, PIF1, ZFP1) or auxin signaling (ATHB8 and AHL14). Co-expression has also been observed with factors from the brassinosteroid signaling (BAG7 with EVE1, which has been implied in VLFR; HSP81.2). (5) The role of cytoplasmatic processes and vesicle transport in modifying phyA-related responses has to be re-evaluated and further explored.
