Characterization of a β-carotene isomerase from the cyanobacterium Cyanobacteria aponinum

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 379; no. 1914; p. 20230360
• Main Authors: Alvarez, Derry, Yang, Yu, Saito, Yoshimoto, Balakrishna, Aparna, Goto, Kasuke, Gojobori, Takashi, Al-Babili, Salim
• Format: Journal Article
• Language: English
• Published: England 18-11-2024
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; beta Carotene - metabolism; cis-trans-Isomerases - genetics; cis-trans-Isomerases - metabolism; Cyanobacteria - enzymology; Cyanobacteria - genetics; Cyanobacteria - metabolism; Escherichia coli - genetics; Phylogeny; DWARF27 β-carotene isomerase; carotenoids; cyanobacteria; strigolactones
• ISSN: 1471-2970
• DOI: 10.1098/rstb.2023.0360

Carotenoids are essential components of the photosynthetic apparatus and precursors of plant hormones, such as strigolactones (SLs). SLs are involved in various aspects of plant development and stress-response processes, including the establishment of root and shoot architecture. SL biosynthesis begins with the reversible isomerization of all-
-carotene into 9-
-β-carotene, catalysed by DWARF27 β-carotene isomerase (D27). Sequence comparisons have revealed the presence of D27-related proteins in photosynthetic eukaryotes and cyanobacteria lacking SLs. To gain insight into the evolution of SL biosynthesis, we characterized the activity of a cyanobacterial D27 protein (
D27) from
, using carotenoid-accumulating
cells and
enzymatic assays. Our results demonstrate that
D27 is an all-
/
and
/
-β-carotene isomerase, with a
/
conversion preference.
D27 catalysed 13-
/15-
, all-
/9-
-β-carotene, and neurosporene isomerization. Compared with plant enzymes, it exhibited a lower 9-
-/all-
-β-carotene conversion ratio. A comprehensive genome survey revealed the presence of
as a single-copy gene in the genomes of 20 out of 200 cyanobacteria species analysed. Phylogenetic and enzymatic analysis of
D27 indicated that cyanobacterial
genes form a single orthologous group, which is considered an ancestral type of those found in photosynthetic eukaryotes. This article is part of the theme issue 'The evolution of plant meta‌bolism'.