Discovery of an RmlC/D fusion protein in the microalga Prymnesium parvum and its implications for NDP-β-l-rhamnose biosynthesis in microalgae

Ben A Wagstaff, Martin Rejzek, Sakonwan Kuhaudomlarp, Lionel Hill, Ilaria Mascia, Sergey A Nepogodiev, Helge C Dorfmueller, Robert A Field

Research output: Contribution to journalArticlepeer-review


The 6-deoxy sugar l-rhamnose (l-Rha) is found widely in plant and microbial polysaccharides and natural products. The importance of this and related compounds in host-pathogen interactions often means that l-Rha plays an essential role in many organisms. l-Rha is most commonly biosynthesized as the activated sugar nucleotide uridine 5'-diphospho-β-l-rhamnose (UDP-β-l-Rha) or thymidine 5'-diphospho-β-l-rhamnose (TDP-β-l-Rha). Enzymes involved in the biosynthesis of these sugar nucleotides have been studied in some detail in bacteria and plants, but the activated form of l-Rha and the corresponding biosynthetic enzymes have yet to be explored in algae. Here, using sugar-nucleotide profiling in two representative algae, Euglena gracilis and the toxin-producing microalga Prymnesium parvum, we show that levels of UDP- and TDP-activated l-Rha differ significantly between these two algal species. Using bioinformatics and biochemical methods, we identified and characterized a fusion of the RmlC and RmlD proteins, two bacteria-like enzymes involved in TDP-β-l-Rha biosynthesis, from P. parvum Using this new sequence and also others, we explored l-Rha biosynthesis among algae, finding that although most algae contain sequences orthologous to plant-like l-Rha biosynthesis machineries, instances of the RmlC-RmlD fusion protein identified here exist across the Haptophyta and Gymnodiniaceae families of microalgae. On the basis of these findings, we propose potential routes for the evolution of nucleoside diphosphate β-l-Rha (NDP-β-l-Rha) pathways among algae.

Original languageEnglish
Pages (from-to)9172-9185
Number of pages14
JournalJournal of Biological Chemistry
Issue number23
Publication statusPublished - 7 Jun 2019


  • Algal Proteins/genetics
  • Carbohydrate Epimerases/classification
  • Haptophyta/metabolism
  • Phylogeny
  • Plastids/metabolism
  • Recombinant Fusion Proteins/genetics
  • Rhamnose/biosynthesis
  • Symbiosis

Research Beacons, Institutes and Platforms

  • Manchester Institute of Biotechnology


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