Author: Diva Gallo

PLOS Pathogens Celebrates the Winners of the 2012 PLOS Pathogens Molecular Parasitology Talk Awards.

PLOS Pathogens was well represented at the 2012 Annual Molecular Parasitology Meeting (MPM) Meeting last September in Woods Hole, MA. PLOS Pathogens Section Editor, Kami Kim, helped organize the meeting alongside Artur Scherf and Noreen Williams, all leaders in the field of parasitology. The MPM meeting covers many topics including molecular biology, cell biology, biochemistry, genetics and genomics, focusing on protozoan parasites.

For the fifth year in a row, PLOS Pathogens honored three inspiring students selected by a committee of experts in the field, with prizes for outstanding presentations of their research. We would like to congratulate Bjorn F.C. Kafsack (Lewis Sigler Institute for Integrative Genomics at Princeton University), Kevin Brown (University of Oklahoma Health Sciences Center) and Josh Beck (University of California, Los Angeles) who were recognized for presenting the three best student talks of the conference.

Bjorn F.C. Kafsack presented research identifying a DNA binding protein, AP2-G of the human malaria parasite Plasmodium falciparum . This protein is essential for the formation of malaria gametocytes which are necessary for transmission from a human host to the mosquito, a critical step in the parasite lifecycle. Using forward and reverse genetics, Bjorn demonstrated that AP2-G is critical for the formation of gametocytes and identified a number of early gametocyte genes that are controlled by this protein. Bjorn’s work suggests that AP2-G acts as a master regulator of the asexual/sexual differentiation switch that malaria parasites need as part of their life cycle.

Kevin Brown’s work centers around a small molecule inhibitor called SB505124 that potently blocks Toxoplasma gondii growth in an unusual manner.  He found that SB505124 simultaneously targets enzymes called kinases from both the mammalian host and the parasite, thereby disrupting parasite cellular division.  In the host, SB505124 inhibits specific protein targets called Activin-Like Kinase Receptors 4,5, and 7.  Toxoplasma relies on this family of receptors in order to turn on the host transcription factor HIF-1α which is required for parasite growth.  Using directed genetic screening, he found that SB505124 also targets a related enzyme from the parasite called TgMAPK1. He observed that TgMAPK1 localizes to the centrosome complexes of dividing parasites.  Inhibition of this parasite kinase causes centrosome reduplication, disrupting the cell counting mechanism required for proper division of cells.  He further demonstrated that treating strains of Toxoplasma with SB505124 causes them to switch from the fast growing (“tachyzoite”) form to the encysted slow-growing (“bradyzoite”) form.

Josh Beck identified an apicomplexan-specific family of Inner Membrane Complex Sub-compartment Proteins (ISPs) which consists of four proteins in Toxoplasma that localize to distinct  sub-compartments underneath the cell surface membrane. The tachyzoite stage of Toxoplasma tachyzoite usually produces two daughters per round of division.  However disruption of the gene isp2  results in the assembly of aberrant numbers of daughters with a corresponding loss in parasite fitness. Furthermore, a double knockout, which is also missing a second related gene (isp3)  displays more severe defects in daughter counting, strengthening a role for this family in the control of the parasite budding. Additionally, the double knock out (∆isp2/3) parasites regularly fail to properly segregate organelles between forming daughters with many division attempts producing terminal parasite defects. Collectively, these results indicate that the ISPs are novel components of the Toxoplasma internal budding apparatus that are important for controlling daughter dynamics from the mother parasite. Because the ISPs have no identifiable domains that might suggest their functions, Josh took a structural approach to further investigate how they work. Interestingly, 3D structure analysis reveals that the ISPs adopt structures that transduce signals through cells by binding lipids called inositol polyphosphates or through protein-protein interactions.

The awards were announced at the end of the conference.  Each winner received a cash prize of 150 dollars.

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