Our lab is interested in the molecular events that enable apicomplexan parasites to remain widespread and deadly infectious agents. These single-celled eukaryotes comprise a phylum of organisms that parasitize diverse animal hosts. Many important human pathogens belong to this group, including the causative agents of malaria (Plasmodium spp.), cryptosporidiosis (Cryptosporidium spp.), and toxoplasmosis (Toxoplasma gondii). We use T. gondii to model features conserved throughout the phylum, such as their reliance on calcium signaling to regulate motility. We combine several approaches that span phospho-proteomics, chemical-genetics, and genome editing to investigate the unique biology of these organisms. Our work seeks to expand our understanding of eukaryotic diversity and identify specific features that can be targeted to treat parasite infections. For more information on our work, visit iBiology.org for Sebastian’s lectures on Toxoplasma and other stories of cutting-edge research in the life sciences, available for free to a global audience.
HiT the Toxoplasma genome
April 28, 2022. Tyler’s paper on the high-throughput tagging (HiT) of Toxoplasma genes is now published in Nature Microbiology. The paper describes a new method of CRISPR-based screening that manipulates genes through tagging instead of disrupting. Using this approach, we discovered a new regulator of the parasite lytic cycle.
Dr. Tyler A. Smith
April 14, 2022. Tyler successfully defends his thesis on the High-throughput functionalization of the Toxoplasma kinome. Congratulations Dr. Smith!
Dylan receives NSF fellowship
April 14, 2022. Congratulations to Dylan McCormick for receiving one of the National Science Foundation Graduate Research Fellowship Program awards!
Changes in cytosolic calcium regulate eukaryotic cellular responses as diverse as membrane repair and muscle contraction. In apicomplexan parasites, calcium regulates motility in part through the regulation of adhesin exocytosis and myosin-motor function. We seek to understand the molecular details of these processes, examining both the events that lead to cytosolic calcium changes and the signaling events that follow them.
We are interested in how calcium signals are decoded by protein kinases, and in particular the role of calcium-dependent protein kinases (CDPKs) as the primary calcium-responsive kinases in parasites. Our work, and that of many others, has defined diverse roles for these kinases in regulating important events during the life cycle of apicomplexans. We have recently used alpaca-derived single-domain antibodies to probe the structure of CDPKs, defining a new mode of allosteric inhibition. We continue to develop biochemical methods to study these kinases, in addition to chemical-genetic approaches to study their function in vivo.
We have engineered a panel of strains to study individual CDPKs. This approach relies on mutating the “gatekeeper” residue that restricts the depth of the ATP-binding pocket. This allows us to specifically inhibit or identify the targets of individual kinases. Using this approach, we have previously elucidated the distinct roles of TgCDPK1 and TgCDPK3 during the T. gondii lytic cycle. We continue to investigate the functions of these and other CDPKs, relying in part on phospho-proteomic methods to identify specific kinase targets.
Much of our work is made possible through a variety of genome-engineering methods. We are interested in developing new methods to enable efficient functional analysis of parasite genes and polymorphisms. Our lab was among the first to adapt CRISPR/Cas9 to engineer the T. gondii genome, and our plasmids are available to anyone through Addgene. We continue to improve these systems to enable genome-scale screening in parasites, which will allow exploration of the multitude of apicomplexan genes with unknown functions.
Sebastian Lourido Principal Investigator
Gabrielle McCauley Administrative Lab Manager
Emily Shortt Lab Manager
Sundeep Chakladar UROP
Mudita Goyal UROP
Zoe Gotthold UROP
Judson Lam UROP
Justin Roberts Doctoral Student
Chris Giuliano Doctoral Student
Michelle Peters Doctoral Student
Dylan McCormick Doctoral Student
NSF Graduate Research Fellow
Dominic Schwarz Doctoral Student
AHA Predoctoral Fellow
Chinmay Kalluraya Doctoral Student
Dylan Valleau Postdoctoral Fellow
Human Frontier Science Program Fellow
Haley Licon Postdoctoral Fellow
Aditi Shukla Postdoctoral Fellow
Helen Hay Whitney Fellow
Eden Yifrach Postdoctoral Fellow
EMBO Postdoctoral Fellow
Simon Butterworth Postdoctoral Fellow
Aarti Krishnan Visiting Postdoctoral Fellow
Chip & Dale Cats
The multifaceted roles of Myb domain-containing proteins in apicomplexan parasites.
Curr Opin Microbiol. 2023 Dec;76:102395.
A conserved complex of microneme proteins mediates rhoptry discharge in Toxoplasma.
EMBO J. 2023 Dec 1;42(23):e113155.
Translation initiation factor eIF1.2 promotes Toxoplasma stage conversion by regulating levels of key differentiation factors.
bioRxiv [Preprint]. 2023 Nov 3:2023.11.03.565545.
Discovery of antibiotics that selectively kill metabolically dormant bacteria.
2023 Nov 15:S2451-9456(23)00387-2.
SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle.
bioRxiv [Preprint]. 2023 Oct 30:2023.10.30.564746.
CDPK2A and CDPK1 form a signaling module upstream of Toxoplasma motility.
mBio. 2023 Aug 23:e0135823.
A positive feedback loop controls Toxoplasma chronic differentiation.
Licon MH, Giuliano CJ, Chan AW, Chakladar S, Eberhard JN, Shallberg LA, Chandrasekaran S, Waldman BS, Koshy AA, Hunter CA, Lourido S.
Nat Microbiol. 2023 May;8(5):889-904.
Functional profiling of the Toxoplasma genome during acute mouse infection.
bioRxiv. 2023 Mar 6:2023.03.05.531216.
Analysis of CDPK1 targets identifies a trafficking adaptor complex that regulates microneme exocytosis in Toxoplasma.
Chan AW, Broncel M, Yifrach E, Haseley NR, Chakladar S, Andree E, Herneisen AL, Shortt E, Treeck M, Lourido S.