Critical role of 7,8-didemethyl-8-hydroxy-5-deazariboflavin for photoreactivation in Chlamydomonas reinhardtii

Jason L. Petersen, Patrick J. Ronan

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


DNA photolyases use two noncovalently bound chromophores to catalyze photoreactivation, the blue light-dependent repair of DNA that has been damaged by ultraviolet light. FAD is the catalytic chromophore for all photolyases and is essential for photoreactivation. The identity of the second chromophore is often 7,8-didemethyl-8-hydroxy-5-deazariboflavin (FO). Under standard light conditions, the second chromophore is considered nonessential for photoreactivation because DNA photolyase bound to only FAD is sufficient to catalyze the repair of UV-damaged DNA. phr1 is a photoreactivation-deficient strain of Chlamydomonas. In this work, the PHR1 gene of Chlamydomonas was cloned through molecular mapping and shown to encode a protein similar to known FO synthases. Additional results revealed that the phr1 strain was deficient in an FO-like molecule and that this deficiency, as well as the phr1 photoreactivation deficiency, could be rescued by transformation with DNA constructs containing the PHR1 gene. Furthermore, expression of a PHR1 cDNA in Escherichia coli produced a protein that generated a molecule with characteristics similar to FO. Together, these results indicate that the Chlamydomonas PHR1 gene encodes an FO synthase and that optimal photoreactivation in Chlamydomonas requires FO, a molecule known to serve as a second chromophore for DNA photolyases.

Original languageEnglish (US)
Pages (from-to)32467-32475
Number of pages9
JournalJournal of Biological Chemistry
Issue number42
StatePublished - Oct 15 2010
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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