Control of carotenoid biosynthesis through a heme-based cis-trans isomerase

Jesús Beltrán, Brian Kloss, Jonathan P. Hosler, Jiafeng Geng, Aimin Liu, Anuja Modi, John H. Dawson, Masanori Sono, Maria Shumskaya, Charles Ampomah-Dwamena, James D. Love, Eleanore T. Wurtzel

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Plants synthesize carotenoids, which are essential for plant development and survival. These metabolites also serve as essential nutrients for human health. The biosynthetic pathway for all plant carotenoids occurs in chloroplasts and other plastids and requires 15-cis-ζ-carotene isomerase (Z-ISO). It was not known whether Z-ISO catalyzes isomerization alone or in combination with other enzymes. Here we show that Z-ISO is a bona fide enzyme and integral membrane protein. Z-ISO independently catalyzes the cis-trans isomerization of the 15-15′ carbon-carbon double bond in 9,15,9′-cis-ζ-carotene to produce the substrate required by the subsequent biosynthetic-pathway enzyme. We discovered that isomerization depends upon a ferrous heme b cofactor that undergoes redox-regulated ligand switching between the heme iron and alternate Z-ISO amino acid residues. Heme b-dependent isomerization of a large hydrophobic compound in a membrane was previously undescribed. As an isomerase, Z-ISO represents a new prototype for heme b proteins and potentially uses a new chemical mechanism.

Original languageEnglish (US)
Pages (from-to)598-605
Number of pages8
JournalNature Chemical Biology
Issue number8
StatePublished - Aug 23 2015

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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