On the Red Antenna States of Photosystem I Mutants from Cyanobacteria Synechocystis PCC 6803

• DOI: 10.1021/acs.jpcb.0c05201
• Publication Date: 2020-08-27T19:02:15Z
• Authors: Anton Khmelnitskiy; Hila Toporik; Yuval Mazor; Ryszard Jankowiak
• Keywords: Synechocystis

To identify the molecular composition of low-energy states in cyanobacterial Photosystem I (PSI) Synechocystis PCC6803, we focus on high-resolution (low-temperature) absorption, emission, resonant, and nonresonant hole-burned spectra obtained for wild-type (WT) PSI three mutants. In Red_a mutant, B33 chlorophyll (Chl) is added to B31-B32 dimer; Red_b, histidine 95 (His95) PsaB (which coordinates Mg B7 Chl within His95-B7-A31-A32-cluster) replaced with glutamine (Gln), while Red_ab both mutations are made. We show that C706 state (B31-B32) changes C710 (B31-B32-B33) mutants, C707 WT (localized His95-B7-A31-A32 cluster) modified C716 Red_b Red_ab. Excitation energy transfer from C714 trap mutant hampered as reflected by a weak emission at 712 nm. Large electron-phonon coupling strength (exposed via resonant spectra) consistent strong mixing excited intermolecular charge leading significantly red-shifted spectra. conclude excitation controlled fine-tuning electronic small number highly conserved red states. Finally, modify protein potential landscape revealed different shapes shifts blue- antiholes.