|Professor, Microbiology, Immunology & Molecular Genetics|
|Member, Biochemistry, Biophysics & Structural Biology GPB Home Area, California NanoSystems Institute, Cell & Developmental Biology GPB Home Area, Immunity, Microbes & Molecular Pathogenesis GPB Home Area, Microbiology, Immunology & Molecular Genetics|
The eukaryotic flagellum (synonymous with cilium) is a biological nanomachine, composed of thousands of interconnected parts. Flagella and cilia perform essential motility and signaling functions, are conserved in all eukaryotic lineages, and are considered to have been present on the last eukaryotic common ancestor.
Proteomics and genomics have provided an inventory of flagellar proteins, but we lack knowledge of how these are assembled into supramolecular structures that operate individually and collectively to drive motility and signaling by the flagellum. This presents a critical gap in our understanding of one of the most iconic features of eukaryote biology. To fill this gap, we use cryoelectron microscopy (cryoEM) and tomography (cryoET) to determine the 3D architecture of the flagellum. We also employ proteomics, super-resolution microscopy, high-speed video microscopy and animal imaging to define the spatial distribution of proteins within flagellum micro-domains, investigate mechanisms of microbial cell and signaling, and determine how the flagellum controls virulence of microbial pathogens. Our goal is to provide a structural foundation for defining flagellum motility and signaling mechanisms at the molecular level, with models being formally tested through genetic manipulation of component parts.
As an experimental system, my group employs African trypanosomes, parasites that present a global public health burden and limit economic development in some of the most impoverished regions on the planet. The flagellum directs parasite motility and extracellular sensing and is thus essential for transmission and pathogenic capacity of these deadly organisms.
The trypanosome flagellum is also conserved with the human cilium (aka flagellum), which is essential for normal development and physiology. Indeed, cilium defects underlie a broad spectrum of inherited diseases, including retinopathy, renal failure, skeletal abnormalities and obesity. Therefore, beyond their medical and economic importance, trypanosomes are an important model system for studying flagellum/cilium biology. They are easily cultured for biochemical studies and possess a potent array of molecular genetic tools for targeted gene knockout and inducible RNAi. The genome is fully sequenced and annotated and systems biology approaches, e.g. transcriptomics, quantitative proteomics and high-throughput RNAi screens, are well established. Therefore, in addition to host-pathogen interaction, we use our studies to advance understanding of inherited diseases in humans, and provide insights into fundamental features of eukaryotic cell biology.
Langousis Gerasimos, Shimogawa Michelle M, Saada Edwin A, Vashisht Ajay A, Spreafico Roberto, Nager Andrew R, Barshop William D, Nachury Maxence V, Wohlschlegel James A, Hill Kent L Loss of the BBSome perturbs endocytic trafficking and disrupts virulence of Trypanosoma brucei. Proceedings of the National Academy of Sciences of the United States of America. 2016; 113(3): 632-7.
Saada Edwin A, DeMarco Stephanie F, Shimogawa Michelle M, Hill Kent L "With a Little Help from My Friends"-Social Motility in Trypanosoma brucei. PLoS pathogens. 2015; 11(12): e1005272.
Shimogawa Michelle M, Saada Edwin A, Vashisht Ajay A, Barshop William D, Wohlschlegel James A, Hill Kent L Cell Surface Proteomics Provides Insight into Stage-Specific Remodeling of the Host-Parasite Interface in Trypanosoma brucei. Molecular & cellular proteomics : MCP. 2015; 14(7): 1977-88.
Oberholzer Michael, Saada Edwin A, Hill Kent L Cyclic AMP Regulates Social Behavior in African Trypanosomes. mBio. 2015; 6(3): e01954-14.
Lopez Miguel A, Saada Edwin A, Hill Kent L Insect stage-specific adenylate cyclases regulate social motility in African trypanosomes. Eukaryotic cell. 2015; 14(1): 104-12.
Saada Edwin A, Kabututu Z Pius, Lopez Miguel, Shimogawa Michelle M, Langousis Gerasimos, Oberholzer Michael, Riestra Angelica, Jonsson Zophonias O, Wohlschlegel James A, Hill Kent L Insect stage-specific receptor adenylate cyclases are localized to distinct subdomains of the Trypanosoma brucei Flagellar membrane. Eukaryotic cell. 2014; 13(8): 1064-76.
Freire Eden R, Vashisht Ajay A, Malvezzi Amaranta M, Zuberek Joanna, Langousis Gerasimos, Saada Edwin A, Nascimento JanaÃna De F, Stepinski Janusz, Darzynkiewicz Edward, Hill Kent, De Melo Neto Osvaldo P, Wohlschlegel James A, Sturm Nancy R, Campbell David A eIF4F-like complexes formed by cap-binding homolog TbEIF4E5 with TbEIF4G1 or TbEIF4G2 are implicated in post-transcriptional regulation in Trypanosoma brucei. RNA (New York, N.Y.). 2014; 20(8): 1272-86.
Langousis Gerasimos, Hill Kent L Motility and more: the flagellum of Trypanosoma brucei. Nature reviews. Microbiology. 2014; 12(7): 505-18.
Freire Eden R, Malvezzi Amaranta M, Vashisht Ajay A, Zuberek Joanna, Saada Edwin A, Langousis Gerasimos, Nascimento JanaÃna D F, Moura Danielle, Darzynkiewicz Edward, Hill Kent, de Melo Neto Osvaldo P, Wohlschlegel James A, Sturm Nancy R, Campbell David A Trypanosoma brucei translation initiation factor homolog EIF4E6 forms a tripartite cytosolic complex with EIF4G5 and a capping enzyme homolog. Eukaryotic cell. 2014; 13(7): 896-908.
Kisalu Neville K, Langousis Gerasimos, Bentolila Laurent A, Ralston Katherine S, Hill Kent L Mouse infection and pathogenesis by Trypanosoma brucei motility mutants. Cellular microbiology. 2014; 16(6): 912-24.
Nguyen Hoangkim T, Sandhu Jaspreet, Langousis Gerasimos, Hill Kent L CMF22 Is a Broadly Conserved Axonemal Protein and Is Required for Propulsive Motility in Trypanosoma brucei. Eukaryotic cell. 2013; 12(9): 1202-13.
Louise C. Hughes, Katherine S. Ralston, Kent L. Hill1, Z. Hong Zhou Three-Dimensional Structure of the Trypanosome Flagellum Suggests that the Paraflagellar Rod Functions as a Biomechanical Spring. PLoS One 2012; 7(1):e25700. Epub 2012 Jan 3.(1): e25700.
Hughes Louise C, Ralston Katherine S, Hill Kent L, Zhou Z Hong Three-dimensional structure of the Trypanosome flagellum suggests that the paraflagellar rod functions as a biomechanical spring. PloS one. 2012; 7(1): e25700.
Lopez Miguel A, Nguyen HoangKim T, Oberholzer Michael, Hill Kent L Social parasites. Current opinion in microbiology. 2011; 14(6): 642-8.
Oberholzer Michael, Langousis Gerasimos, Nguyen HoangKim T, Saada Edwin A, Shimogawa Michelle M, Jonsson Zophonias O, Nguyen Steven M, Wohlschlegel James A, Hill Kent L Independent analysis of the flagellum surface and matrix proteomes provides insight into flagellum signaling in mammalian-infectious Trypanosoma brucei. Molecular & cellular proteomics : MCP. 2011; 10(10): M111.010538.
Ralston Katherine S, Kisalu Neville K, Hill Kent L Structure-function analysis of dynein light chain 1 identifies viable motility mutants in bloodstream-form Trypanosoma brucei. Eukaryotic cell. 2011; 10(7): 884-94.
Merveille et al. CCDC39 is required for assembly of inner dynein arms and the dynein regulatory complex and for normal ciliary motility in humans and dogs. . Nature Genetics. 2011; 43: 72-78.
Oberholzer,M., Langousis,G., Nguyen,H., Saada, E., Shimogawa, M., Jonsson, Z., Nguyen, S., Wohlschlegel, J.A. and Hill, K.L. Independent analysis of the flagellum surface and matrix proteomes provides insight into flagellum signaling in mammalian-infectious Trypanosoma brucei. Mol. & Cell. Proteomics 2011; Oct;10(10):M111.010538. Epub 2011 Jun 19.: .
Lopez, M.A. Nguyen, H.T. Oberholzer, M. Hill, K.L. Social Parasites. Curr. Opin. Microbiol 2011; In Press: .
Ralston, K.R. Kisalu, N.K. Hill, K.L. Structure-function analysis of dynein light chain 1 identifies viable motility mutants in bloodstream-form Trypanosoma brucei . Euk Cell 2011; In Press: .
Kabututu Zakayi P, Thayer Michelle, Melehani Jason H, Hill Kent L CMF70 is a subunit of the dynein regulatory complex. Journal of cell science. 2010; 123(Pt 20): 3587-95.
Hill Kent L Parasites in motion: flagellum-driven cell motility in African trypanosomes. Current opinion in microbiology. 2010; 13(4): 459-65.
Kabututu, P.K. Thayer, M. Melehani, J.H. Hill, K.L. CMF70 is a subunit of the dynein regulatory complex. J. Cell Science 2010; 123: 3587-95.
Oberholzer, M., Lopez, M., McLelland, B., Hill, K.L. Social motility in African trypanosomes. PLoS Pathogens 2010; Jan 29;6(1):e1000739: .
Oberholzer Michael, Lopez Miguel A, McLelland Bryce T, Hill Kent L Social motility in african trypanosomes. PLoS pathogens. 2010; 6(1): e1000739.
Oberholzer, M. Lopez, MA, Ralston, KS, Hill, KL Approaches for functional analysis of flagellar proteins in African trypanosomes. Methods in Cell Biology 2009; 93: 21-57.
Rodríguez,JA, Lopez, MA, Thayer, MC, Zhao, Y, Oberholzer, M, Chang, D, Kisalu, NK, Penichet, ML, Helguera, G, Bruinsma, R, Hill, KL and Miao, J Propulsion of African trypanosomes is driven by bihelical waves with alternating chirality separated by kinks. Proc. Natl. Acad. Sci 2009; 106(46): 19322-19327.
Ralston, K.S., Kabututu, Z.P., Melehani, J.H., Oberholzer, M. Hill, K.L. The Trypanosoma brucei flagellum: moving parasites in new directions. Annual Review of Microbiology 2009; 63: 335-62.
Colantonio, JR, Vermot, J., Wu, D. Langenbacher, A., Fraser, S. Chen, JN and Hill, K.L. The dynein regulatory complex is required for ciliary motility and otolith biogenesis in the inner ear. Nature. 2009; 457: 205-209.
Oberholzer Michael, Lopez Miguel A, Ralston Katherine S, Hill Kent L Approaches for functional analysis of flagellar proteins in African trypanosomes. Methods in cell biology. 2009; 93(7226): 21-57.
Ralston Katherine S, Kabututu Zakayi P, Melehani Jason H, Oberholzer Michael, Hill Kent L The Trypanosoma brucei flagellum: moving parasites in new directions. Annual review of microbiology. 2009; 63(7226): 335-62.
Colantonio Jessica R, Vermot Julien, Wu David, Langenbacher Adam D, Fraser Scott, Chen Jau-Nian, Hill Kent L The dynein regulatory complex is required for ciliary motility and otolith biogenesis in the inner ear. Nature. 2009; 457(7226): 205-9.
Ralston Katherine S, Hill Kent L The flagellum of Trypanosoma brucei: new tricks from an old dog. International journal for parasitology. 2008; 38(8-9): 869-84.
Ralston, K.S. and Hill, K.L. The flagellum of Trypanosoma brucei: new tricks from an old dog. Intl. J. Parasitol. 2008; 38: 869-864.
Bekker, J.M., J.R. Colantonio, A.D. Stephens, W.T. Clarke, S.J. King, K.L. Hill, and R.H. Crosbie. Direct Interaction of Gas11 with Microtubules: Implications for the Dynein Regulatory Complex. Cell Motility and the Cytoskeleton. Cell Motility and the Cytoskeleton. 2007; 64: 461-473.
Baron, D. M., Ralston, K. S., Kabututu, Z. P. and Hill, K. L. Functional Genomics in Trypanosoma brucei Identifies Evolutionarily-Conserved Components of Motile Flagella. J. Cell Science. 2007; 120: 478-491.
Baron, D. M. Kabututu, Z. P. Hill, K. L Stuck in reverse: loss of the dynein light chain LC1 disrupts outer dynein arms, and leads to reverse flagellar beat and backward cell movement in Trypanosoma brucei. J. Cell Science. 2007; 120: 1513-1520.
Bekker Janine M, Colantonio Jessica R, Stephens Andrew D, Clarke W Thomas, King Stephen J, Hill Kent L, Crosbie Rachelle H Direct interaction of Gas11 with microtubules: implications for the dynein regulatory complex. Cell motility and the cytoskeleton. 2007; 64(6): 461-73.
Baron Desiree M, Kabututu Zakayi P, Hill Kent L Stuck in reverse: loss of LC1 in Trypanosoma brucei disrupts outer dynein arms and leads to reverse flagellar beat and backward movement. Journal of cell science. 2007; 120(Pt 9): 1513-20.
Baron Desiree M, Ralston Katherine S, Kabututu Zakayi P, Hill Kent L Functional genomics in Trypanosoma brucei identifies evolutionarily conserved components of motile flagella. Journal of cell science. 2007; 120(Pt 3): 478-91.
Colantonio JR, Bekker JM, Kim SJ, Morrissey KM, Crosbie RH and Hill KL Expanding the Role of the Dynein Regulatory Complex to Non-Axonemal Functions:. Traffic. 2006; 7(5): 538-548.
Ralston KS, Lerner AL, Deiner DR and Hill KL Flagellar motility contributes to cytokinesis in Trypanosoma brucei and is modulated by an evolutionarily-conserved dynein regulatory system. . Euk. Cell. 2006; 5, 696-711: .
Ralston, K.S., and K.L. Hill. Trypanin, a comonent of a flagellar dynein regulatory complex, is essential in bloodstream-form Trypanosoma brucei. . PLoS Pathogens. 2006; 2(9): 873-882.
Hill KL Biology and mechanism of trypanosome cell motility. Euk. Cell. . 2003; 2(2): 200-8.
Yi CE, Bekker JM, Miller G, Hill KL, Crosbie RH Specific and potent RNA interference in terminally differentiated myotubes. J. Biol. Chem. . 2003; 278(2): 934-9.
Hutchings NR, Donelson JE, Hill KL Trypanin is a cytoskeletal linker protein and is required for cell motility in African trypanosomes. J. Cell Biol. . 2002; 156(5): 867-77.
Hill KL, Hutchings NR, Grandgenett PM, Donelson JE T lymphocyte-triggering factor of african trypanosomes is associated with the flagellar fraction of the cytoskeleton and represents a new family of proteins that are present in several divergent eukaryotes. J. Biol. Chem. 2000; 275(50): 39369-78.
LaCount DJ, Bruse S, Hill KL and Donelson JE Double-stranded RNA interference in Trypanosoma brucei. Mol. Biochem. Parasitol 2000; 111: 67-76.
Hill KL, Hutchings NR, Russell DG and Donelson JE A novel protein targeting domain confers flagellar pocket targeting in African trypanosomes. J. Cell Science. 1999; 112: 3091-3101.
Hill KL and Donelson JE Antigenic variation in microbial pathogens. The Encyclopedia of Genetics 1999; .
Hill KL and Coughlin BC Gene rearrangement in eukaryotic organisms. The Encyclopedia of Genetics 1999; .
Teixeira SM, Otsu K, Hill KL, Kirchhoff LV, Donelson JE Expression of a marker for intracellular Trypanosoma cruzi amastigotes in extracellular spheromastigotes. Mol. Biochem. Parasitol. 1999; 98(2): 265-70.
Donelson JE, Hill KL, El-Sayed NM Multiple mechanisms of immune evasion by African trypanosomes. Mol. Biochem. Parasitol. 1998; 91(1): 51-66.
Vaidya T, Bakhiet M, Hill KL, Olsson T, Kristensson K, Donelson JE The gene for a T lymphocyte triggering factor from African trypanosomes. J. Exp. Med . 1997; 186(3): 433-8.
Hill KL, Catlett NL, Weisman LS Actin and myosin function in directed vacuole movement during cell division in Saccharomyces cerevisiae. J. Cell Biol. 1996; 135(6 Pt 1): 1535-49.