Structure of GUN4 from Chlamydomonas reinhardtii

Shabnam Tarahi Tabrizi, David B. Langley, Stephen J. Harrop, Anthony P. Duff, Robert D. Willows*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
38 Downloads (Pure)


The genomes uncoupled 4 (GUN4) protein stimulates chlorophyll biosynthesis by increasing the activity of Mg-chelatase, the enzyme that inserts magnesium into protoporphyrin IX (PPIX) in the chlorophyll biosynthesis pathway. One of the roles of GUN4 is in binding PPIX and Mg-PPIX. In eukaryotes, GUN4 also participates in plastid-to-nucleus signalling, although the mechanism for this is unclear. Here, the first crystal structure of a eukaryotic GUN4, from Chlamydomonas reinhardtii, is presented. The structure is in broad agreement with those of previously solved cyanobacterial structures. Most interestingly, conformational divergence is restricted to several loops which cover the porphyrin-binding cleft. The conformational dynamics suggested by this ensemble of structures lend support to the understanding of how GUN4 binds PPIX or Mg-PPIX.

Original languageEnglish
Pages (from-to)1094-1099
Number of pages6
JournalActa Crystallographica. Section F: Structural Biology Communications
Publication statusPublished - 1 Aug 2015

Bibliographical note

Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • Chlorophyll biosynthesis
  • Genomes uncoupled
  • Magnesium chelatase
  • Plastid signalling
  • Protoporphyrin


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