Regensburg 2019 – scientific programme

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BP: Fachverband Biologische Physik

BP 1: Protein structure and dynamics

BP 1.6: Talk

Monday, April 1, 2019, 11:30–11:45, H4

LOVely aureochromes: Time-resolved small-angle X-ray scattering reveals the global structure recovery time of the multidomain photoreceptor — •Saskia Bannister, Elena Herman, Thomas Hellweg, and Tilman Kottke — Bielefeld University, Germany

Aureochromes (AUREO) function as blue-light-regulated transcription factors in algae.[1] Their basic region/leucine zipper (bZIP) effector domain binds DNA with a specific sequence while a light-, oxygen-, or voltage-sensitive (LOV) domain acts as the C-terminal sensor. In the dark, LOV binds flavin non-covalently while upon illumination an adduct is formed. Due to their unusual domain arrangement AUREOs are versatile candidates for new synthetic optogenetic tools. We therefore characterized a full-length AUREO1c variant (38 kDa) and found that its quantum yield of adduct formation is exceptionally low. Furthermore, we applied time-resolved small-angle X-ray scattering (SAXS) on an inhouse setup to investigate the recovery of the overall structure of AUREO1c in the dark. Additionally, the recovery kinetics of the flavin was determined by UV/vis spectroscopy under similar conditions. These studies revealed a discrepancy between the lifetime of the flavin adduct and the global structural recovery time of the multidomain photoreceptor. We therefore conclude that an additional spectrally silent intermediate exists that significantly prolongs the lifetime of the signalling state.

[1] Takahashi et al. (2007), PNAS 104, 19625-19630.