The C-terminal region affects the activity of photoactivated adenylyl cyclase from Oscillatoria acuminata

Abstract

Photoactivated adenylyl cyclase (PAC) is a unique protein that, upon blue light exposure, catalyzes cAMP production. The crystal structures of two PACs, from Oscillatoria acuminata (OaPAC) and Beggiatoa sp. (bPAC), have been solved, and they show a high degree of similarity. However, the photoactivity of OaPAC is much lower than that of bPAC, and the regulatory mechanism of PAC photoactivity, which induces the difference in activity between OaPAC and bPAC, has not yet been clarified. Here, we investigated the role of the C-terminal region in OaPAC, the length of which is the only notable difference from bPAC. We found that the photoactivity of OaPAC was inversely proportional to the C-terminal length. However, the deletion of more than nine amino acids did not further increase the activity, indicating that the nine amino acids at the C-terminal critically affect the photoactivity. Besides, absorption spectral features of light-sensing domains (BLUF domains) of the C-terminal deletion mutants showed similar light-dependent spectral shifts as in WT, indicating that the C-terminal region influences the activity without interacting with the BLUF domain. The study characterizes new PAC mutants with modified photoactivities, which could be useful as optogenetics tools.

Light-Induced Change of Arginine Conformation Modulates the Rate of Adenosine Triphosphate to Cyclic Adenosine Monophosphate Conversion in the Optogenetic System Containing Photoactivated Adenylyl Cyclase

“…Lindner et al reported the results of structural, kinetic, and mutational studies in bPAC, which were interpreted on the base of the obtained crystal structures of the protein in the dark and light-illuminated (shortly, light) states of the BLUF domains containing flavin mononucleotide (FMN) cofactors but bearing no substrates or substrate analogues in the AC domains. These results are consistent with those obtained in studies of the homologous OaPAC protein ,, in respect that small structural changes occur upon dark to light transition. The authors of ref assumed that highly conserved residues of the BLUF domain, Tyr7 and Gln49, the kink in β4 BLUF , and the C-terminal BLUF capping helix were involved in the signaling pathway.…”

Molecular Mechanism of Light-Induced Acceleration of the Adenosine Triphosphate Conversion to the Cyclic Adenosine Monophosphate Catalyzed by the Photoactivated Adenylyl Cyclase bPAC

“…Lindner et al 15 reported the results of structural, kinetic and mutational studies in bPAC, which were interpreted on the base of the obtained crystal structures of the protein in the dark and light-illuminated (shortly, light) states of the BLUF domains containing flavin mononucleotide (FMN) cofactors, but bearing no substrates or substrate analogs in the AC domains. These results 15 are consistent with those obtained in studies of the homologues OaPAC protein 12,13,21 in respect that small structural changes occur upon dark-to-light transition. The authors of Ref 15 assumed that highly conservative residues of BLUF domain, Tyr7 and Gln49, the kink in β4BLUF and the C-terminal BLUF capping helix were involved in the signaling pathway.…”

Molecular Mechanism of Light-Induced Acceleration of the Adenosine Triphosphate Conversion to the Cyclic Adenosine Monophosphate Catalyzed by the Photoactivated Adenylyl Cyclase bPAC

“…Lindner et al 15 reported the results of structural, kinetic and mutational studies in bPAC, which were interpreted on the base of the obtained crystal structures of the protein in the dark and light-illuminated (shortly, light) states of the BLUF domains containing flavin mononucleotide (FMN) cofactors, but bearing no substrates or substrate analogs in the AC domains. These results 15 are consistent with those obtained in studies of the homologues OaPAC protein 12,13,21 in respect that small structural changes occur upon dark-to-light transition. The authors of Ref 15 assumed that highly conservative residues of BLUF domain, Tyr7 and Gln49, the kink in β4BLUF and the C-terminal BLUF capping helix were involved in the signaling pathway.…”