Thomas E. Sladewski & Aoife T. Heaslip. Molecular features of Myosin F adapted for driving actin flows in Toxoplasma gondii. J Cell Sci. 2026 Apr 1;139(7). Issue cover.

‍This study uses a broad set of techniques including single molecule imaging, in vitro motility, single particle negative stain electron microscopy, proteomics, and ultrastructure expansion microscopy to determine how a molecular motor unique to Toxoplasma gondii drives intracellular cargo transport. ‍

Thomas E. Sladewski & Aoife T. Heaslip. Cell contractility: Myosin-II-mediated contraction of fast-crawling amoebae. Curr Biol. 2025 Dec 1;35(23).

Wenxiang Cao*, Thomas E. Sladewski*, Aoife T. Heaslip, Enrique M. De La Cruz. Bending stiffness of Toxoplasma gondii actin filaments. J Biol Chem. 2025 Feb;301(2):108101. Asterisks denote equal contribution.

The unique D-loop of T. gondii filament allowed us to address how loss of lateral contacts affects actin filament stiffness. We found that despite being more dynamic, this actin isoform has the same mechanical properties as skeletal actin. A conserved magnesium binding site present in both filaments is what appears to control actin stiffness.

Kelli L. Hvorecny*, Thomas E. Sladewski*, Enrique M. De La Cruz, Justin M. Kollman, Aoife T. Heaslip. Toxoplasma gondii actin filaments are tuned for rapid disassembly and turnover. Nat Commun. 2024 Feb 28;15(1):1840. Asterisks denote equal contribution.

We characterized the in vitro properties of purified T. gondii actin. In collaboration with Justin Kollman’s lab (Washington University) and Enrique De La Cruz (Yale University), we reveal the structural and biochemical basis for the inherent instability of T. gondii actin.

Thomas E. Sladewski, Paul C. Campbell, Neil Billington, Alexandra D'Ordine, James L. Cole, Christopher L. de Graffenried. Cytokinesis in Trypanosoma brucei relies on an orphan kinesin that dynamically crosslinks microtubules. Curr Biol. 2023 Mar 13;33(5):899-911.e5.

This work uses a single molecule in vitro approach to uncover a novel microtubule-based mechanism for kinetoplastid cytokinesis.

Richard S. Muniz, Paul C. Campbell, Thomas E. Sladewski, Lars D. Renner, Christopher L. de Graffenried. Revealing spatio-temporal dynamics with long-term trypanosomatid live-cell imaging. PLoS Pathog. 2022 Jan 18;18(1):e1010218.

Amy N. Sinclair, Christine T. Huynh, Thomas E. Sladewski, Jenna L. Zuromski, Amanda E. Ruiz, Christopher L. de Graffenried. The Trypanosoma brucei subpellicular microtubule array is organized into functionally discrete subdomains defined by microtubule associated proteins. PLoS Pathog. 2021 May 19;17(5):e1009588.

Nicholas A. Hilton, Thomas E. Sladewski, Jenna A. Perry, Zemplen Pataki, Amy N. Sinclair-Davis, Richard S. Muniz, Holly L. Tran, Jenna I. Wurster, Jiwon Seo, Christopher L. de Graffenried. Identification of TOEFAZ1-interacting proteins reveals key regulators of Trypanosoma brucei cytokinesis. Mol Microbiol. 2018 Aug;109(3):306-326.

Thomas E. Sladewski*, Neil Billington*, M Yusuf Ali*, Carol S. Bookwalter, Hailong Lu, Elena B. Krementsova, Trina A. Schroer, Kathleen M. Trybus.Recruitment of two dyneins to an mRNA-dependent Bicaudal D transport complex. eLife. 2018 Jun 26;7. Asterisks denote equal contribution.

In collaboration with Dr. Trina Schroer (Johns Hopkins), we reconstitute mRNA transport in higher eukaryotes from purified dynein, dynactin, BicD and a synthetic mRNA transcript and visualize them “walking” on microtubules in vitro at a single molecule level. This work highlights how the principles of mRNA transport in budding yeast are conserved in mammals, despite using different classes of molecular motors.

Thomas E. Sladewski, Elena B. Krementsova, and Kathleen M. Trybus. Myosin Vc is specialized for transport on a secretory superhighway. Curr Biol. 2016 Aug 22;26(16):2202-7.

Thomas E. Sladewski, Kathleen M. Trybus. A single molecule approach to mRNA transport by a class V myosin. RNA Biol. 2014;11(8):986-91.

Thomas E Sladewski, Carol S Bookwalter, Myoung-Soon Hong, Kathleen M Trybus. Single-molecule reconstitution of mRNA transport by a class V myosin. Nat Struct Mol Biol. 2013 Aug;20(8):952-7. Issue Cover

In this work, we fully reconstitute a Myo4p-mRNA complex (mRNP) from purified components and use single molecule techniques to show that mRNA and mRNA-binding proteins are required to activate Myo4p for transport by stabilizing a functional two-headed motor complex that is capable of moving processively when bound to mRNA cargo.

Alex R. Hodges, Elena B. Krementsova, Carol S. Bookwalter, Patricia M. Fagnant, Thomas E. Sladewski, Kathleen M. Trybus. Tropomyosin is essential for processive movement of a class V myosin from budding yeast. Curr Biol. 2012 Aug 7;22(15):1410-6.

Elena B. Krementsova, Alex R. Hodges, Carol S. Bookwalter, Thomas E. Sladewski, Mirko Travaglia, H. Lee Sweeney, Kathleen M. Trybus. Two single-headed myosin V motors bound to a tetrameric adapter protein form a processive complex. J Cell Biol. 2011 Nov 14;195(4):631-41.

Matthew R. Sammons, Michael L. James, Joseph E. Clayton, Thomas E. Sladewski, Vladimir Sirotkin, Matthew Lord. A calmodulin-related light chain from fission yeast that functions with myosin-I and PI 4-kinase. J Cell Sci. 2011 Jul 15;124(Pt 14):2466-77.

Thomas E. Sladewski, Kyle M. Hetrick, Patricia L. Foster. Escherichia coli Rep DNA helicase and error-prone DNA polymerase IV interact physically and functionally. Mol Microbiol. 2011 Apr;80(2):524-41.

Benjamin C. Stark*, Thomas E. Sladewski*, Luther W. Pollard, Matthew Lord. Tropomyosin and myosin-II cellular levels promote actomyosin ring assembly in fission yeast. Mol Biol Cell. 2010 Mar 15;21(6):989-1000. Asterisks denote equal contribution.

Thomas E. Sladewski, Michael J. Previs, Matthew Lord. Regulation of fission yeast myosin-II function and contractile ring dynamics by regulatory light-chain and heavy-chain phosphorylation. Mol Biol Cell. 2009 Sep;20(17):3941-52.

Matthew Lord, Thomas E. Sladewski, Thomas D. Pollard. Yeast UCS proteins promote actomyosin interactions and limit myosin turnover in cells. Proc Natl Acad Sci U S A. 2008 Jun 10;105(23):8014-9.

Thomas E. Sladewski, Alicia M. Shafer, Craig M. Hoag. The effect of ionic strength on the UV-vis spectrum of congo red in aqueous solution. Spectrochim Acta A Mol Biomol Spectrosc. 2006 Nov;65(3-4):985-7.