Completed Cells, Biochemistry & Physiology Infection & Immunity

Molecular mechanisms of encystation and sporulation.

In plain English

AI plain-English summary

Many single-celled parasites wrap themselves in tough, protective shells to survive hostile environments, and this project aims to find the genetic switches that control that process. This matters because these shells—called cysts—allow pathogens like *Legionella*, *Vibrio cholerae*, and MRSA to hitch rides inside amoebas, surviving immune attacks, antibiotics, and even airborne dispersal. The mechanisms behind encystation are largely unknown because most encysting organisms are difficult to genetically manipulate. The researchers have found that a social amoeba called *Polysphondylium pallidum* is uniquely suited for both forward and reverse genetics, and they have already identified several encystation genes that are deeply conserved across protozoa—including one target now being explored for anti-encystation drug development with the Dundee Drug Discovery Unit. If this research succeeds, it could lead to drugs that prevent pathogenic protists from forming cysts, making them vulnerable to immune clearance and antibiotics. This would directly impact treatment of infections that currently resist standard therapies. The work is primarily fundamental science—uncovering the genetic pathways that control encapsulation in amoebas and their evolutionary origins—but it has a clear translational path toward new antimicrobial compounds.

View original technical description
Most protozoa survive environmental stress by encapsulating to form a cyst or spore. This process is medically important for pathogenic protists since cysts are resistant to immune clearance, antibiotics and biocides. Cysts of bacterivorous protists such as Acanthamoeba additionally act as vectors for airborne dispersal of bacterial pathogens, such as Legionella pneumoniae, Vibrio cholerae and MRSA. Due to the limited genetic tractibility of encysting organisms, the mechanisms controlling encyst ation are largely unknown. Dictyostelid social amoebas survive stress by building fruiting structures with encapsulated spores and stalk cells. Both cell types mature in response to PKA activation, and we showed that this process is derived from encystation in solitary amoebas, which we found to also require cAMP acting on PKA. The encysting Dictyostelid Polysphondylium pallidum is uniquely suitable for both reverse and forward genetic approaches, allowing us to identify several encystation gene s, which proved to be deeply conserved in protozoa. This included one suitable target for anti-encystation drug development, which we are currently exploring in collaboration with the Dundee Drug Discovery Unit. In our future research we will combine the power of genetics with proteomics and drug development to achieve the following goals: Find all genes that control encystation in P.pallidum and the order in which they interact. Investigate functional conservation of essential genes in path ogenic protists and instigate compound screens to find inhibitors. Identify missing links in the pathways that regulate spore and stalk cell encapsulation in Dictyostelia and establish how these pathways emerged from the ancestral encystation pathway.

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Researchers

Pauline Schaap (EPMC Awardee)

Related Research

Grants with similar aims, by meaning.

Molecular mechanisms of encystation.
Molecular processes essential for parasite sporogony.
Comparative genome analysis in social amoebas
Sphingolipid biosynthesis in the parasitic apicomplexan protozoa: divergent enzymes in key host:pathogen interactions
Mechanisms of spore engulfment in C. difficile

Original classification

Investigator Award in Science

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