Path to the brown coloration of diatoms discovered

Natural waters around the world are home to diatoms. They take up a lot of carbon dioxide and convert it into energy. The blue-green part of the sunlight is able to be Harvested by Diatoms with the help of the Carotenoids.

Researchers from Johannes Gutenberg University Mainz in Germany collaborated with an international research team to discover how the algae produce this important and widely used pigment. Their paper was published in the PNAS.

There are new insights into fucoxanthin.

Up to one-fifth of the global carbon dioxide fixation can be attributed to the diatoms, the most species-rich algal group. The leaves of land plants are green in color. Their distinct color is due to the light-harvesting carotenoid fucoxanthin that allows the efficient absorption and utilization of the blue-green light in many aquatic habitats. One of the main drivers of marine photosynthesis is fucoxanthin.

Fucoxanthin has become a topic of increasing interest for pharmaceutical applications. The chemical structure of fucoxanthin was established in the 1960's, 150 years after it was first mentioned in the scientific literature. It was not known how the product was created.

The biosynthetic pathway of fucoxanthin has been discovered by the research groups of Dr. Martin Lohr at Johannes Gutenberg University Mainz, Professor Graham Peers at Colorado State University, and Professor Xiaobo Li at Westlake University.

The researchers used the CRISPR/Cas9 genetic scissors to impair the genes in the diatom Phaeodactylum tricornutum that are involved in the production of carotenoids. The green-colored mutants that were knockout were devoid of fucoxanthin but had other carotenoids instead. The researchers were able to propose the complete path to fucoxanthin with the help of the detailed biochemical characterization.

A complex pathway is used to synthesise.

The pathway was much more complex than anticipated. The researchers were able to show that the fucoxanthin pathway evolved from the duplication of ancient genes for the purpose of catalyzing the formation of photo protection.

Carotenoids were initially used as protectants under light. The work shows that diatoms duplicate components of the enzymatic toolbox. The synthesis of more complex carotenoids was made possible by some of the copies that gained novel functions. The evolutionary younger brown algae don't have these new intermediates. They appear to have modified the pathway by shortening it.

Transferring the complete fucoxanthin biosynthetic pathway into other organisms is not currently possible. The pathway intermediates have been identified, but some of the enzymes involved are not known. The authors believe that their findings will lead to the identification of the missing enzymes. A deeper understanding of the biogenesis and regulation of the photosynthetic apparatus will be provided by the green diatom mutants.

More information: Yu Bai et al, Green diatom mutants reveal an intricate biosynthetic pathway of fucoxanthin, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2203708119 Journal information: Proceedings of the National Academy of Sciences Citation: Path to the brown coloration of diatoms discovered (2022, September 15) retrieved 15 September 2022 from https://phys.org/news/2022-09-path-brown-diatoms.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.