Dataset Information

Cloning and Functional Characterization of Cycloartenol Synthase from the Red Seaweed Laurencia dendroidea.

ABSTRACT: The red seaweed Laurencia dendroidea belongs to the Rhodophyta, a phylum of eukaryotic algae that is widely distributed across the oceans and that constitute an important source of bioactive specialized metabolites. Laurencia species have been studied since 1950 and were found to contain a plethora of specialized metabolites, mainly halogenated sesquiterpenes, diterpenes and triterpenes that possess a broad spectrum of pharmacological and ecological activities. The first committed step in the biosynthesis of triterpenes is the cyclization of 2,3-oxidosqualene, an enzymatic reaction carried out by oxidosqualene cyclases (OSCs), giving rise to a broad range of different compounds, such as the sterol precursors cycloartenol and lanosterol, or triterpene precursors such as cucurbitadienol and ?-amyrin. Here, we cloned and characterized the first OSC from a red seaweed. The OSC gene was identified through mining of a L. dendroidea transcriptome dataset and subsequently cloned and heterologously expressed in yeast for functional characterization, which indicated that the corresponding enzyme cyclizes 2,3-oxidosqualene to the sterol precursor cycloartenol. Accordingly, the gene was named L. dendroidea cycloartenol synthase (LdCAS). A phylogenetic analysis using OSCs genes from plants, fungi and algae revealed that LdCAS grouped together with OSCs from other red algae, suggesting that cycloartenol could be the common product of the OSC in red seaweeds. Furthermore, profiling of L. dendroidea revealed cholesterol as the major sterol accumulating in this species, implicating red seaweeds contain a 'hybrid' sterol synthesis pathway in which the phytosterol precursor cycloartenol is converted into the major animal sterol cholesterol.

SUBMITTER: Calegario G

PROVIDER: S-EPMC5104453 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Cloning and Functional Characterization of Cycloartenol Synthase from the Red Seaweed Laurencia dendroidea.

Calegario Gabriela G Pollier Jacob J Arendt Philipp P de Oliveira Louisi Souza LS Thompson Cristiane C Soares Angélica Ribeiro AR Pereira Renato Crespo RC Goossens Alain A Thompson Fabiano L FL

PloS one 20161110 11

The red seaweed Laurencia dendroidea belongs to the Rhodophyta, a phylum of eukaryotic algae that is widely distributed across the oceans and that constitute an important source of bioactive specialized metabolites. Laurencia species have been studied since 1950 and were found to contain a plethora of specialized metabolites, mainly halogenated sesquiterpenes, diterpenes and triterpenes that possess a broad spectrum of pharmacological and ecological activities. The first committed step in the bi ...[more]

PMID: 27832119

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Project description:BackgroundSeaweeds of the Laurencia genus have a broad geographic distribution and are largely recognized as important sources of secondary metabolites, mainly halogenated compounds exhibiting diverse potential pharmacological activities and relevant ecological role as anti-epibiosis. Host-microbe interaction is a driving force for co-evolution in the marine environment, but molecular studies of seaweed-associated microbial communities are still rare. Despite the large amount of research describing the chemical compositions of Laurencia species, the genetic knowledge regarding this genus is currently restricted to taxonomic markers and general genome features. In this work we analyze the transcriptomic profile of L. dendroidea J. Agardh, unveil the genes involved on the biosynthesis of terpenoid compounds in this seaweed and explore the interactions between this host and its associated microbiome.ResultsA total of 6 transcriptomes were obtained from specimens of L. dendroidea sampled in three different coastal locations of the Rio de Janeiro state. Functional annotations revealed predominantly basic cellular metabolic pathways. Bacteria was the dominant active group in the microbiome of L. dendroidea, standing out nitrogen fixing Cyanobacteria and aerobic heterotrophic Proteobacteria. The analysis of the relative contribution of each domain highlighted bacterial features related to glycolysis, lipid and polysaccharide breakdown, and also recognition of seaweed surface and establishment of biofilm. Eukaryotic transcripts, on the other hand, were associated with photosynthesis, synthesis of carbohydrate reserves, and defense mechanisms, including the biosynthesis of terpenoids through the mevalonate-independent pathway.ConclusionsThis work describes the first transcriptomic profile of the red seaweed L. dendroidea, increasing the knowledge about ESTs from the Florideophyceae algal class. Our data suggest an important role for L. dendroidea in the primary production of the holobiont and the role of Bacteria as consumers of organic matter and possibly also as nitrogen source. Furthermore, this seaweed expressed sequences related to terpene biosynthesis, including the complete mevalonate-independent pathway, which offers new possibilities for biotechnological applications using secondary metabolites from L. dendroidea.

Project description:In Laurencia dendroidea, halogenated secondary metabolites are primarily located in the vacuole named the corps en cerise (CC). For chemical defence at the surface level, these metabolites are intracellularly mobilised through vesicle transport from the CC to the cell periphery for posterior exocytosis of these chemicals. The cell structures involved in this specific vesicle traffic as well as the cellular structures related to the positioning and anchoring of the CC within the cell are not well known. Here, we aimed to investigate the role of cytoskeletal elements in both processes. Cellular and molecular assays were conducted to i) determine the ultrastructural apparatus involved in the vesicle traffic, ii) localise cytoskeletal filaments, iii) evaluate the role of different cytoskeletal filaments in the vesicle transport, iv) identify the cytoskeletal filaments responsible for the positioning and anchoring of the CC, and v) identify the transcripts related to cytoskeletal activity and vesicle transport. Our results show that microfilaments are found within the connections linking the CC to the cell periphery, playing an essential role in the vesicle traffic at these connections, which means a first step of the secondary metabolites transport to the cell surface. After that, the microtubules work in the positioning of the vesicles along the cell periphery towards specific regions where exocytosis takes place, which corresponds to the second step of the secondary metabolites transport to the cell surface. In addition, microtubules are involved in anchoring and positioning the CC to the cell periphery. Transcriptomic analysis revealed the expression of genes coding for actin filaments, microtubules, motor proteins and cytoskeletal accessory proteins. Genes related to vesicle traffic, exocytosis and membrane recycling were also identified. Our findings show, for the first time, that actin microfilaments and microtubules play an underlying cellular role in the chemical defence of red algae.

Dataset Information

Cloning and Functional Characterization of Cycloartenol Synthase from the Red Seaweed Laurencia dendroidea.

Publications

Cloning and Functional Characterization of Cycloartenol Synthase from the Red Seaweed Laurencia dendroidea.

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