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bioRxiv · 10.1101/2022.04.06.487258

D27-LIKE1 carotenoid isomerase has a preference towards trans/cis and cis/cis conversions in Arabidopsis

Gulyas, Z.·Moncsek, B.·Hamow, K. A.·Straner, P.·Badics, E.·Incze, N.·Darko, E.·Nagy, V.·Perczel, A.·Kovacs, L.·Soos, V.
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Abstract

Carotenoids are colourful isoprenoids that contribute to a variety of physiological processes in plants. They also function as biosynthesis precursors of abscisic acid (ABA) and strigolactones (SLs). SL biosynthesis starts with the enzymatic conversion of all-trans-{beta}-carotene to 9-cis-{beta}-carotene by the DWARF27 (D27) isomerase. In Arabidopsis, D27 has two closely related paralogs, D27-LIKE1 and D27-LIKE2 which were predicted to be {beta}-carotene-isomerases. Here we characterised D27-LIKE1 and identified some key aspects of its function. Arabidopsis d27-like1-1 mutant does not display any SL or karrikin-deficient traits, however, it exhibits a substantially higher 9-cis-violaxanthin content. In vitro feeding assays with recombinant D27-LIKE1 revealed that the protein exhibits affinity to all {beta}-carotene isoforms but with an exclusive preference towards trans/cis conversions and the interconversion between 9-cis, 13-cis and 15-cis-{beta}-carotene forms. Feeding experiments with zeaxanthin and violaxanthin isomers revealed that D27-LIKE1 accepts these xanthophylls as substrates. The remarkably higher 9-cis-violaxanthin content of the mutant is accompanied by a slightly higher ABA level. Finally, we presented evidence that D27-LIKE1 mRNA is phloem mobile and D27-LIKE1 is an ancient isomerase with long evolutionary history. In summary, we demonstrated that D27-LIKE1 is a carotenoid isomerase with multi-substrate specificity and has a characteristic preference towards the catalysation of cis/cis interconversion of carotenoids. Therefore, D27-LIKE1 is a potential regulator of carotenoid cis pools and eventually, SL and ABA biosynthesis pathways.

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Gulyas, Z., Moncsek, B., Hamow, K. A., Straner, P., Badics, E., Incze, N., Darko, E., Nagy, V., Perczel, A., Kovacs, L., Soos, V.. 2022-04-08. D27-LIKE1 carotenoid isomerase has a preference towards trans/cis and cis/cis conversions in Arabidopsis. https://doi.org/10.1101/2022.04.06.487258

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