IUBMB Enzyme Nomenclature


Accepted name: phytochromobilin:ferredoxin oxidoreductase

Reaction: (3Z)-phytochromobilin + oxidized ferredoxin = biliverdin IXα + reduced ferredoxin

For diagram click here.

Other name(s): HY2; PΦB synthase; phytochromobilin synthase

Systematic name: (3Z)-phytochromobilin:ferredoxin oxidoreductase

Comments: Catalyses the two-electron reduction of biliverdin IXα. Can use [2Fe-2S] ferredoxins from a number of sources as acceptor but not the [4Fe-4S] ferredoxin from Clostridium pasteurianum. The isomerization of (3Z)-phytochromobilin to (3E)-phytochromobilin is thought to occur prior to covalent attachment to apophytochrome in the plant cell cytoplasm. Flavodoxins can be used instead of ferredoxin.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 138263-99-7


1. Frankenberg, N., Mukougawa, K., Kohchi, T. and Lagarias, J.C. Functional genomic analysis of the HY2 family of ferredoxin-dependent bilin reductases from oxygenic photosynthetic organisms. Plant Cell 13 (2001) 965-978. [PMID: 11283349]

2. McDowell, M.T. and Lagarias, J.C. Purification and biochemical properties of phytochromobilin synthase from etiolated oat seedlings. Plant Physiol. 126 (2001) 1546-1554. [PMID: 11500553]

3. Terry, M.J., Wahleithner, J.A. and Lagarias, J.C. Biosynthesis of the plant photoreceptor phytochrome. Arch. Biochem. Biophys. 306 (1993) 1-15. [PMID: 8215388]

[EC created 2002]

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