8QFG

Cryogenic crystal structure of the Photoactivated Adenylate Cyclase OaPAC after 5 seconds of blue light illumination

Summary for 8QFG

• Entry DOI: 10.2210/pdb8qfg/pdb
• Descriptor: Family 3 adenylate cyclase, FLAVIN MONONUCLEOTIDE, ADENOSINE-5'-TRIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: photoreceptor, bluf, adenylate cyclase, pac, lyase
• Biological source: Oscillatoria acuminata PCC 6304
• Total number of polymer chains: 1
• Total formula weight: 40304.98

Authors

Chretien, A.,Nagel, M.F.,Botha, S.,de Wijn, R.,Brings, L.,Doerner, K.,Han, H.,C.P.Koliyadu, J.,Letrun, R.,Round, A.,Sato, T.,Schmidt, C.,Secareanu, R.,von Stetten, D.,Vakili, M.,Wrona, A.,Bean, R.,Mancuso, A.,Schulz, J.,R.Pearson, A.,Kottke, T.,Lorenzen, K.,Schubert, R. (deposition date: 2023-09-04, release date: 2023-11-01, Last modification date: 2024-03-13)

Primary citation

Chretien, A.,Nagel, M.F.,Botha, S.,de Wijn, R.,Brings, L.,Dorner, K.,Han, H.,Koliyadu, J.C.P.,Letrun, R.,Round, A.,Sato, T.,Schmidt, C.,Secareanu, R.C.,von Stetten, D.,Vakili, M.,Wrona, A.,Bean, R.,Mancuso, A.,Schulz, J.,Pearson, A.R.,Kottke, T.,Lorenzen, K.,Schubert, R.
Light-induced Trp in /Met out Switching During BLUF Domain Activation in ATP-bound Photoactivatable Adenylate Cyclase OaPAC.
J.Mol.Biol., 436:168439-168439, 2024

PubMed Abstract: The understanding of signal transduction mechanisms in photoreceptor proteins is essential for elucidating how living organisms respond to light as environmental stimuli. In this study, we investigated the ATP binding, photoactivation and signal transduction process in the photoactivatable adenylate cyclase from Oscillatoria acuminata (OaPAC) upon blue light excitation. Structural models with ATP bound in the active site of native OaPAC at cryogenic as well as room temperature are presented. ATP is found in one conformation at cryogenic- and in two conformations at ambient-temperature, and is bound in an energetically unfavorable conformation for the conversion to cAMP. However, FTIR spectroscopic experiments confirm that this conformation is the native binding mode in dark state OaPAC and that transition to a productive conformation for ATP turnover only occurs after light activation. A combination of time-resolved crystallography experiments at synchrotron and X-ray Free Electron Lasers sheds light on the early events around the Flavin Adenine Dinucleotide (FAD) chromophore in the light-sensitive BLUF domain of OaPAC. Early changes involve the highly conserved amino acids Tyr6, Gln48 and Met92. Crucially, the Gln48 side chain performs a 180° rotation during activation, leading to the stabilization of the FAD chromophore. Cryo-trapping experiments allowed us to investigate a late light-activated state of the reaction and revealed significant conformational changes in the BLUF domain around the FAD chromophore. In particular, a Trp/Met transition upon illumination is observed for the first time in the BLUF domain and its role in signal transmission via α-helix 3 and 4 in the linker region between sensor and effector domain is discussed.

PubMed: 38185322
DOI: 10.1016/j.jmb.2024.168439

Experimental method

X-RAY DIFFRACTION (1.7 Å)