Dichromic Allophycocyanin Trimer Covering a Broad Spectral Range (550-660 nm).

Area of Science:

• Biochemistry
• Photosynthesis research
• Biotechnology

Background:

• Phycobilisomes are crucial light-harvesting complexes in cyanobacteria and red algae.
• Their complex structure and assembly hinder applications in photonics and fluorescence labeling.
• Understanding chromophore roles is key to overcoming assembly obstacles.

Purpose of the Study:

• To investigate the role of chromophores in phycobilisome core assembly.
• To engineer novel light-harvesting complexes with altered spectral properties.
• To develop efficient artificial light-harvesting elements.

Main Methods:

• Genetic modification of biliverdin reductases in Synechocystis sp. PCC 6803.
• Introduction of green-absorbing phycoerythrobilin instead of phycocyanobilin.
• In vitro generation and purification of a novel trimeric allophycocyanin (Dic-APC) using a core-linker.

Main Results:

• Replacing phycocyanobilin with phycoerythrobilin inhibited phycobilisome aggregation.
• A novel, trimeric allophycocyanin (Dic-APC) was successfully generated.
• The Dic-APC unit (110 kDa) contains phycoerythrobilin and phytochromobilin, covering 550-660 nm.
• Efficient energy transfer was observed within Dic-APC, demonstrating its potential as a light-harvesting element.

Conclusions:

• Chromophore composition significantly impacts phycobilisome assembly and properties.
• Engineered Dic-APC serves as an efficient artificial light-harvesting element with broad spectral range.
• Template-assisted purification and linker labeling offer methods for Dic-APC production and targeting.