- Daniel Portnoy
- Bacterial pathogenesis
- Professor, Molecular and Cell Biology and School of Public Health
- 508 Barker Hall
- Berkeley, CA 94720-3202
- Phone 510.643.3925
- Lab Phone 510.643.3926
- Fax 510.643.6334
Professor, Division of Biochemistry, Biophysics, and Structural Biology, Dept. of Molecular & Cell Biology and Division of Infectious Diseases and Vaccinology, School of Public Health.
Edward E. Penhoet Distinguished Chair in Global Public Health and Infectious Diseases.
Affiliate, Division of Immunology & Pathogenesis, Dept. of Molecular & Cell Biology. Affiliate, Graduate Group in Microbiology, Dept. of Plant & Microbial Biology.
The overall goal of our research is to understand the molecular and cellular basis of microbial pathogenesis and the mechanisms used by the host to defend against infection. Specifically, the lab is focused on the interaction of the facultative intracellular bacterial pathogen Listeria monocytogenes and its mammalian host. This fascinating microorganism is able to enter cells, escape from a phagosome, circumvent autophagy, avoid cell death pathways and grow rapidly in the cytosol. By exploiting a host system of actin-based motility, the bacteria move through the cytosol to the cell membrane and into pseudopod-like projections (listeriopods) that are ingested by neighboring cells. This mechanism allows pathogens to spread from one cell to another without ever leaving the host cytoplasm thereby avoiding the immune response.
Escape from a vacuole and cell to cell spread of L. monocytogenes. The stippled material depicts F-actin.
Current ProjectsCell 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. We have recently discovered how LLO exploits endocytosis to mediate internalization of LLO-induced pores in the cytoplasmic membrane.
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. 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 both bacterial growth and 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.
Reniere ML, Whiteley AT, Portnoy DA. (2016). An in vivo selection to identify how Listeria monocytogenes recognizes the intracellular environment. PLoS Pathog. 2016 Jul 14;12(7):e1005741.
Burke TP and Portnoy DA. (2016). SpoVG is a conserved RNA-binding protein that regulates Listeria monocytogenes lysozyme resistance, virulence, and swarming motility. MBio. 2016 Apr 5;7(2). Pii: e00240-16. doi: 10.1128/mBio.00240-16.
McKay SL and Portnoy DA. (2015). Ribosome hibernation facilitates tolerance of stationary-phase bacteria to aminoglycosides. Antimicrob Agents Chemother. 2015 Nov;59(11):6992-9.
Whiteley AT, Pollock AJ, Portnoy DA. (2015). 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.
Kellenberger CA, Chen C, Whiteley AT, Portnoy DA, Hammond MC. (2015). 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.
Mitchell G, Ge L, Huang Q, Chen C, Kianian S, Roberts M, Schekman R, Portnoy DA. (2015). Avoidance of autophagy mediated by PlcA or ActA is required for Listeria monocytogenes growth in macrophages. Infect Immun. 2015 May;83(5):2175-84.
Siegrist MS, Aditham A, Espaillat A, Cameron T, Whiteside S, Cava F, Portnoy DA, Bertozzi CR. (2015). Host actin polymerization tunes the cell division cycle of an intracellular pathogen. Cell Rep. 2015 Apr 15. pii: S2211-1247(15)00325-3.
Reniere ML, Whiteley AT, Hamilton KL, John SM, Lauer P, Brennan RG, Portnoy DA. (2015). Glutathione activates virulence gene expression of an intracellular pathogen. Article. Nature. 2015 Jan 8:517(7533):170-3.
Durack J, Burke TP, Portnoy DA. (2015). A prl mutation in secY suppresses secretion and virulence defects of Listeria monocytogenes secA2 mutants. J. Bacteriol. 2015 Mar;197(5):932-42.
Kline B, McKay S, Tang W, Portnoy DA. (2015). 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):581-91.
Burke TP, Loukitcheva A, Zemansky J, Wheeler R, Boneca IG, Portnoy DA. (2014). Listeria monocytogenes is resistant to lysozyme by the regulation, not acquisition, of cell wall modifying enzymes. J. Bacteriol. (2014) J. Bacteriol. 2014 Nov;196(21):3756-67.
Archer KA, Durack J, and Portnoy DA. (2014). STING-dependent Type I IFN production inhibits cell-mediated immunity to Listeria monocytogenes. PLoS Pathog. 2014 Jan;10(1):e1003861.