Heterologous expression of the C-terminal antigenic domain of the malaria vaccine candidate Pfs48/45 in the green algae Chlamydomonas reinhardtii.

Malaria is a widespread and infectious disease that is a leading cause of death in many parts of the world. Eradication of malaria has been a major world health goal for decades, but one that still remains elusive. Other diseases have been eradicated using vaccination, but traditional vaccination methods have thus far been unsuccessful for malaria. Infection by Plasmodium species, the causative agent of malaria, is currently treated with drug-based therapies, but an increase in drug resistance has led to the need for new methods of treatment. A promising strategy for malaria treatment is to combine transmission blocking vaccines (TBVs) that prevent spread of disease with drug-based therapies to treat infected individuals. TBVs can be developed against surface protein antigens that are expressed during parasite reproduction in the mosquito. When the mosquito ingests blood from a vaccinated individual harboring the Plasmodium parasite, the antibodies generated by vaccination prevent completion of the parasites life-cycle. Animal studies have shown that immunization with Pfs48/45 results in the production of malaria transmission blocking antibodies; however, the development of this vaccine candidate has been hindered by poor expression in both prokaryotic and eukaryotic hosts. Recently, the chloroplast of Chlamydomonas reinhardtii has been used to express complex recombinant proteins. In this study, we show that the C-terminal antigenic region of the Pfs48/45 antigen can be expressed in the chloroplast of the green algae C. reinhardtii and that this recombinant protein has a conformation recognized by known transmission blocking antibodies. Production of this protein in algae has the potential to scale to the very large volumes required to meet the needs of millions at risk for contracting malaria.

Steps toward a globally available malaria vaccine: harnessing the potential of algae for future low cost vaccines.

Malaria is an infectious disease that threatens half of the world's population. This debilitating disease is caused by infection from parasites of the genus Plasmodium. Insecticides, bed nets and drug therapies have lowered the prevalence and death rate associated with malaria but this disease continues to plague many populations around the world. In recent years, many organizations have suggested developing methods for a complete eradication of malaria. The most straightforward and effective method for this potential eradication will be through the development of a low-cost vaccine. To achieve eradication, it will be necessary to develop new vaccine candidates and novel systems for both the production and delivery of these vaccines. Recently, the green algae Chlamydomonas reinhardtii has been used for the recombinant expression of malaria vaccine candidates including the transmission blocking vaccine candidate Pfs48/45. Here, we discuss the potential of this research on the future development of a low-cost malaria vaccine candidate.

Algae biofuels: versatility for the future of bioenergy.

The world continues to increase its energy use, brought about by an expanding population and a desire for a greater standard of living. This energy use coupled with the realization of the impact of carbon dioxide on the climate, has led us to reanalyze the potential of plant-based biofuels. Of the potential sources of biofuels the most efficient producers of biomass are the photosynthetic microalgae and cyanobacteria. These versatile organisms can be used for the production of bioethanol, biodiesel, biohydrogen, and biogas. In fact, one of the most economic methods for algal biofuels production may be the combined biorefinery approach where multiple biofuels are produced from one biomass source.

Probing the in vivo biosynthesis of scytonemin, a cyanobacterial ultraviolet radiation sunscreen, through small scale stable isotope incubation studies and MALDI-TOF mass spectrometry.

Scytonemin is a dimeric indole phenolic pigment found in the sheaths of many cyanobacteria. This pigment absorbs UV radiation protecting subtending cyanobacterial cells from harmful effects. Based on scytonemin's unique chemical structure, the pathway to its biosynthesis is uncertain, thus motivating the current investigation. Herein, we report the incorporation of both tyrosine and tryptophan into scytonemin, and provide in vivo data supporting the tryptophan origin of the ketone carbon involved in the condensation of the two biosynthetic precursors. This study also reports on the new use of a small-scale, MALDI-TOF mass spectrometry technique to monitor the incorporation of isotopically labeled tyrosine during scytonemin biosynthesis.

Significant natural product biosynthetic potential of actinorhizal symbionts of the genus frankia, as revealed by comparative genomic and proteomic analyses.

Bacteria of the genus Frankia are mycelium-forming actinomycetes that are found as nitrogen-fixing facultative symbionts of actinorhizal plants. Although soil-dwelling actinomycetes are well-known producers of bioactive compounds, the genus Frankia has largely gone uninvestigated for this potential. Bioinformatic analysis of the genome sequences of Frankia strains ACN14a, CcI3, and EAN1pec revealed an unexpected number of secondary metabolic biosynthesis gene clusters. Our analysis led to the identification of at least 65 biosynthetic gene clusters, the vast majority of which appear to be unique and for which products have not been observed or characterized. More than 25 secondary metabolite structures or structure fragments were predicted, and these are expected to include cyclic peptides, siderophores, pigments, signaling molecules, and specialized lipids. Outside the hopanoid gene locus, no cluster could be convincingly demonstrated to be responsible for the few secondary metabolites previously isolated from other Frankia strains. Few clusters were shared among the three species, demonstrating species-specific biosynthetic diversity. Proteomic analysis of Frankia sp. strains CcI3 and EAN1pec showed that significant and diverse secondary metabolic activity was expressed in laboratory cultures. In addition, several prominent signals in the mass range of peptide natural products were observed in Frankia sp. CcI3 by intact-cell matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). This work supports the value of bioinformatic investigation in natural products biosynthesis using genomic information and presents a clear roadmap for natural products discovery in the Frankia genus.