- Postdoctoral Fellow, Rockefeller University. Damon Runyon Walter Winchell Cancer Fund postdoctoral fellowship
- PhD - Microbiology & Immunology, University of Washington, Seattle
- BA - Bacteriology, University of California, Los Angeles
- PH 102
- PH 262
- MCB 103
- PMB 103
- Intracellular pathogens
- Listeria monocytogenes
- Cell biology
- Innate and adaptive immunity
Cell biology of infection. The primary L. monocytogenes determinant responsible for lysis of host cell vacuoles is the pore-forming cytolysin, listeriolysin O (LLO). We will continue to focus on the control of LLO synthesis and secretion, and its mechanism of action. The ultimate goal is to relate structural and biochemical information to its precise mechanism of action in both tissue culture and in mice. We are also characterizing a number of fail-safe mechanisms that prevent LLO toxicity in the host cytosol and thereby compartmentalize its activity to acidic vacuoles. Interestingly, mutants that fail to properly compartmentalize LLO activity are cytotoxic to infected host cells and attenuated for virulence in mice.
Innate immunity to infection. Murine listeriosis is an outstanding model to study basic aspects of innate and acquired cell-mediated immunity. Using bacterial mutants blocked at various stages in the infection process, we are elucidating pathways of host cell gene expression in response to microbial infection. Our studies clearly document the presence of a vacuolar and cytosolic pathway of innate immune recognition. Most recently, we identified that bacteria secrete a small signaling molecule, c-di-AMP, through bacterial multidrug efflux pumps that activates a host cytosolic protein called STING leading to the transcription of type I interferon and co-regulated genes. We are currently investigating the role of this pathway during infection and immunity.
Bacterial determinants that control pathogenesis. We continue to use genetic screens and genomic approaches to identify and characterize bacterial determinants required for pathogenesis. Among the bacterial factors we are currently studying include enzymes that synthesize, degrade, and export c-di-AMP during bacterial growth both in culture and in cells. Most recently, we've identified a set of bacterial factors that respond to redox stress and are specifically necessary for growth in macrophages. Bacterial and host derived glutathione are required to activate bacterial virulence gene expression.
Acquired immunity to infection and vaccine development. Mice that survive a challenge with sublethal doses of virulent L. monocytogenes acquire antigen-specific cell-mediated immunity that renders the mice resistant to subsequent challenge. Importantly, killed bacteria or bacterial mutants unable to access the host cell cytosol fail to induce immunity, while mutants that enter the cytosol, but fail to spread from cell to cell retain their capacity to induce immunity. We are interested on both the bacterial and host factors that contribute to immunity. Surprisingly, in the context of L. monocytogenes immunity, the STING pathway has a negative impact on development of adaptive immunity. These studies have implications for the rational design of vaccines. Indeed, L. monocytogenes is being developed in the private sector as a vector-based vaccine for both cancer immunotherapy and infectious diseases applications.
Portman, JL, Huang, Q, Reniere, ML, Iavarone, AT, Portnoy DA. Activity of the pore-forming virulence factor Listeriolysin O is reversibly inhibited by naturally occurring S-glutathionylation. Infect Immun. 2017 Mar 23;85(4). (2017).
Whiteley, AT, Garelis NE, Peterson BN, Choi PH, Tong L, Woodward JJ, Portnoy DA. c-di-AMP modulates Listeria monocytogenes central metabolism to regulate growth, antibiotic resistance, and osmoregulation. Mol Microbiol. 2017 Apr;104(2):212-233. (2017).
Xiong X, Jiao J, Gregory AE, Wang P, Bi Y, Wang X, Jiang Y, Wen B, Portnoy DA, Samuel JE, Chen C. Identification of Coxiella burnetti CD8+ epitopes and delivery by attenuated Listeria monocytogenes as a vaccine vector in a C57BL/6 mouse model. J Infect Dis. 2017 May 15;215(10):1580-1589. (2016).
Reniere, ML. Whiteley, AT. Portnoy, DA. An in vivo selection to identify how Listeria monocytogenes recognizes the intracellular environment. PLoS Pathog. 2016 Jul 14;12(7):e1005741. (2016).
Burke TP and Portnoy DA. SpoVG is a conserved RNA-binding protein that regulates Listeria monocytogenes lysozyme resistance, virulence, and swarming motility. MBio. 2016 Apr 5;7(2). (2016).
McKay SL and Portnoy DA. Ribosome hibernation facilitates tolerance of stationary-phase bacteria to aminoglycosides. Antimicrob Agents Chemother. 2015 Nov;59(11):6992-9. (2015).
Whiteley AT, Pollock AJ, Portnoy DA. The PAMP c-di-AMP Is Essential for Listeria monocytogenes Growth in Rich but Not Minimal Media, due to a Toxic Increase in (p)ppGpp. Cell Host Microbe. 2015 Jun 10;17(6):788-98. (2015).
Kellenberger CA, Chen C, Whiteley AT, Portnoy DA, Hammond MC. RNA-based fluorescent biosensors for live cell imaging of second messenger cyclic di-AMP. J Am Chem Soc. 2015 May 27;137(20):6432-5 (2015).
Mitchell G, Ge L, Huang Q, Chen C, Kianian S, Roberts M, Schekman R, Portnoy DA. Avoidance of autophagy mediated by PlcA or ActA is required for Listeria monocytogenes growth in macrophages. Infect Immun. 2015 May;83(5):2175-84. (2015).
Fu J, Kanne DB, Leong M, Hix Glickman L, McWhirter SM, Lemmens E, Mechette K, Leong JJ, Lauer P, Liu W, Sivick KE, Zeng Q, Soares KC, Zheng L, Portnoy DA, Woodward JJ, Pardoll DM, Dubensky Jr TW, Kim Y. STING agonist formulated cancer vaccines can cure established tumor resistant to PD-1 blockade. Sci Transl Med. 2015 Apr 15;7(283):283ra52. (2015).
Siegrist MS, Aditham A, Espaillat A, Cameron T, Whiteside S, Cava F, Portnoy DA, Bertozzi CR. Host actin polymerization tunes the cell division cycle of an intracellular pathogen. Cell Rep. 2015 Apr 15. pii: S2211-1247(15)00325-3. (2015).
Reniere ML, Whiteley AT, Hamilton KL, John SM, Lauer P, Brennan RG, Portnoy DA. Glutathione activates virulence gene expression of an intracellular pathogen. Article. Nature. 2015 Jan 8:517(7533):170-3. (2015).
Durack J, Burke TP, Portnoy DA. A prl mutation in secY suppresses secretion and virulence defects of Listeria monocytogenes secA2 mutants. J. Bacteriol. 2015 Mar;197(5):932-42. (2015).
Kline B, McKay S, Tang W, Portnoy DA. The Listeria monocytogenes hibernation-promoting factor (HPF) is required for the formation of 100S ribosomes, optimal fitness, and pathogenesis. J Bacteriol. 2015 Feb 1;197(3). (2015).
Burke TP, Loukitcheva A, Zemansky J, Wheeler R, Boneca IG, Portnoy DA. Listeria monocytogenes is resistant to lysozyme by the regulation, not acquisition, of cell wall modifying enzymes. J. Bacteriol. 2014 196(21):3756-67. (2014)
Archer KA, Durack J, and Portnoy DA. STING-dependent Type I IFN production inhibits cell-mediated immunity to Listeria monocytogenes. PLoS Pathog. 2014 Jan;10(1). (2014)
Witte CE, Whiteley AT, Burke TP, Sauer, JD, Portnoy DA, Woodward JJ. Cyclic di-AMP is critical for Listeria monocytogenes growth, cell wall homeostasis, and establishment of infection. mBio. 2013 May 28;4(3). (2013)
Manzanillo, P.S., Shiloh, M.U., Portnoy, DA, Cox, J.S. Mycobacterium tuberculosis activates the DNA-dependent cytosolic surveillance pathway within macrophages. Cell Host Microbe. 11:469-480. (2012).
Melton-Witt, J.A., McKay, S.L., Portnoy, DA. Development of single-gene, signature-tag-based approach in combination with alanine mutagenesis to identify listeriolysin O residues critical for the in vivo survival of Listeria monocytogenes. Infect Immun. 80(6):2221-30. Epub 2012 Mar 26. (2012).
Witte, C.E., Archer, K.A., Rae, C.S., Sauer, J.D., Woodward, J.J., and Portnoy, DA. Innate immune pathways triggered by Listeria monocytogenes and their role in the induction of cell-mediated immunity. Review. Advances in Immunology. 113: 135-156. (2012).
Sauer, JD., Peryere, S., Archer, K.A., Hanson, B., Lauer, P., Portnoy, DA. Listeria monocytogenes engineered to activate the Nlrc4 inflammasome are severely attenuated and fail to induce protective immunity. Proc. Natl. Acad. Sci. USA. 108(30):12419-24. (2011).
Woodward, J.J., A.T. Iavarone, Portnoy, DA. c-di-AMP secreted by intracellular Listeria monocytogenes activates a host type I interferon response. Science. 328: 1703-1705. (2010).
Sauer, John-Demian, C.E. Witte, J. Zemansky, B. Hanson, P. Lauer, and Portnoy, DA. Listeria monocytogenes triggers AIM2-mediated pyroptosis upon infrequent bacteriolysis in the macrophage cytosol. Cell Host Microbe.7(5):412-9. (2010).
Vance RE, Isberg, RR, Portnoy DA. Patterns of pathogenesis: discrimination of pathogenic and nonpathogenic microbes by the innate immune system. Cell Host Microbe. 2009 Jul 23;6(1):10-21. Review. (2009)
Bahjat, K.S., N. Meyer-Morse, E.E. Lemmens, J.A. Shugart, T.W. Dubensky, Jr., D.G. Brockstedt, and Portnoy, D.A. Suppression of cell-mediated immunity following recognition of phagosome-confined bacteria. PLoS Pathog. 5(9):e1000568. (2009).
Zemansky, J., B. Kline, J.J. Woodward, J. H. Leber, H, Marquis, and Portnoy, D.A. Development of a mariner-based transposon and identification of Listeria monocytogenes determinants, including the peptidyl-proline isomerase, PrsA2, that contribute to its hemolytic phenotype. J Bacteriol.191(12):3950-64. (2009).
Crimmins, G. T., A. A. Herskovits, K. Rehder, K.E. Sivick, P. Lauer, T. W. Dubensky, and Portnoy, D.A. Listeria monocytogenes multi-drug efflux resistance transporters activate a cytosolic surveillance pathway of innate immunity. Proc Natl Acad Sci, U S A. 105(29):10191-6. (2008).
Leber, J. H., G. T. Crimmins, S. Raghavan, N. P. Meyer-Morse, J. S. Cox, and D. A. Portnoy. Distinct TLR- and NLR-mediated transcriptional responses to an intracellular pathogen. PloS Pathogens. 4(1):e6 (2008).