Part:BBa_K5052321

PsbF Cytochrome b559 Beta Subunit

About

PsbF encodes the beta subunit of cytochrome b559 in photosystem II. It forms a heterodimer with the alpha subunit to form cytochrome b559 ¹. Cytochrome b559 is crucial for the assembly and functionality of photosystem II, mutation in either of the subunits causes the inability of the cell to assemble photosystem II ². It is thought that cytochrome b559 assists in preventing photoinhibition by accepting excess electrons from electron donors to prevent the formation of reactive oxygen species that will damage the cell ¹. The expression of the alpha and beta subunits of cytochrome b559 are controlled by the psbEFLJ operon in tandem repeats whose copy number is controlled by the conditions the cells are grown in whether that be photoheterotrophic conditions or photoautotrophic conditions.

We sought to improve the electricity generation of our cyanobacterial strains and to do so, overexpression of both subunits in cytochrome b559 would allow for more stable assembly of PSII and increase the efficiency of electricity generation. This would also mean that the expression of cytochrome b559 would be more independent of the environment controlled psbEFLJ operon. Furthermore, the anti-photonhibitory properties of cytochrome b559 make it useful for the creation of a biophotovoltaic cell, where the intensities of light can reach up to 2000 μmol photons m^-2 s^{-1 3}.

References

(1) Chiu, Y.-F.; Chu, H.-A. New Structural and Mechanistic Insights Into Functional Roles of Cytochrome B559 in Photosystem II. Front. Plant Sci. 2022, 13. doi.org/10.3389/fpls.2022.914922.

(2) Pakrasi, H. B.; Williams, J. G.; Arntzen, C. J. Targeted Mutagenesis of the psbE and psbF Genes Blocks Photosynthetic Electron Transport: Evidence for a Functional Role of Cytochrome B559 in Photosystem II. EMBO J. 1988, 7 (2), 325–332.

(3) PPFD to Lux Conversion. www.apogeeinstruments.com/conversion-ppfd-to-lux/ (accessed 2024-09-30).

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]