Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 3: Protein Structure and Dynamics
BP 3.7: Vortrag
Montag, 7. März 2016, 11:45–12:00, H44
Photo-dynamics of photoactivated adenylyl cyclase LiPAC from the spirochete bacterium Leptonema illini strain 3055 — •Alfons Penzkofer1, Meenakshi Tanwar2, Sindu Kandoth Veetil2, and Suneel Kateriya2,3 — 1Fakultät für Physik, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany — 2Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India — 3School of Biotechnology, JNU, New Delhi 110067, India
The photoactivated adenylyl cyclase LiPAC from the spirochete bacterium Leptonema illini was synthesized and characterized by absorption and fluorescence spectroscopic methods [1]. LiPAC consists of a BLUF domain and an adenylyl cyclase homology domain. Photo-excitation of fully oxidized flavin in LiPAC resulted in a typical primary BLUF domain photo-cycle dynamics. The quantum efficiency of BLUF domain signaling state formation was determined to be 0.60. Continued blue-light-excitation of LiPAC in the light-adapted state caused irreversible photo-degradation of non-covalently bound flavin to covalently bound fully reduced flavin with a quantum efficiency of 1.1×10−5. At 20 ∘C the time constant of signaling state recovery to the receptor state after excitation light switch-off was 2.6 s. The protein thermal stability was studied by stepwise sample heating and cooling. A LiPAC melting temperature of 54 ∘C was determined. Schemes of the primary BLUF domain photo-cycling dynamics and the secondary BLUF domain photo-degradation in the signaling state are presented.
[1] A. Penzkofer et al., Trends in Applied Spectroscopy 11 (2014) 39.