Cyanobacteria dynamically regulate phycobilisome-to-photosystem excitation energy transfer
Ivo H.M. van Stokkum,
Dariusz M. Niedzwiedzki,
Parveen Akhtar,
Avratanu Biswas,
Petar H. Lambrev,
Haijun Liu
Affiliations
Ivo H.M. van Stokkum
Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands; Corresponding author
Dariusz M. Niedzwiedzki
Center for Solar Energy and Energy Storage, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Energy Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
Parveen Akhtar
HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
Avratanu Biswas
Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands; HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
Petar H. Lambrev
HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
Haijun Liu
Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
Summary: In cyanobacteria and red algae, the phycobilisome (PBS) absorbs light and transfers its energy to the chlorophylls in photosystems II (PSII) and I (PSI). With the help of target analysis of time-resolved emission spectra measured at room temperature (RT) and at 77 K, we establish a general kinetic scheme for excitation energy transfer (EET) and trapping based upon a PBS-PSII-PSI megacomplex. At RT it is found that in the dark-adapted cells (State II), the terminal emitter of PBS, allophycocyanin APC680, transfers energy to PSII and PSI with equal rates of ≈50 ns−1, and that spillover from PSII to PSI is present with rate ≈6 ns−1. At 77 K, upon transition from State I to State II the EET rate from APC680 to PSII is constant, whereas the rate to PSI increases by 67%. This indicates that a structural change in EET distance in the PBS-PSII-PSI megacomplex underlies the state transition.
