[Hsiu-An Chu] Tandem gene amplification restores photosystem II accumulation in cytochrome b559 mutants of cyanobacteriaPOST:
In this work, we revealed a unique mechanism used by cyanobacteria to cope with mutation-induced instability of photosynthetic protein subunits. Cytochrome (Cyt) b559 is a key component of the photosystem II complex (PSII) that is essential for its proper functioning and assembly. Site-directed mutants of the model cyanobacterium Synechocystis sp. PCC6803 with mutated heme axial-ligands of Cyt b559 have little PSII and are thus unable to grow photoautotrophically. However, we identified two types of Synechocystis autotrophic transformants that retained the same mutations in b559 but are able to accumulate PSII and grow photoautotrophically. Through collaborations with Dr. Josef Komenda and coworker at the Czech Academy of Sciences, we demonstrated that the autotrophic transformants compensated for mutation-destabilized Cyt b559 subunits via multiple tandem amplifications of chromosomal segments containing the mutated psbEFLJ operon. Our results illustrate how tandem gene amplification restores PSII accumulation and photoautotrophic growth in Cyt b559 mutants of cyanobacteria, and may serve as an important adaptive mechanism for cyanobacterial survival. This work is now published on line in New Phytologist.
Chiu YF, Fu HY, Skotnicová P, Lin KM, Komenda J*, Chu HA* Tandem gene amplification restores photosystem II accumulation in cytochrome b559 mutants of cyanobacteria, New Phytologist, First published: 09 October 2021