P. Scott Hefty

P. Scott Hefty
  • Professor
  • MB Chair
  • Director and PI, Center for Chemical Biology of Infectious Disease (CoBRE)


Molecular Mechanisms of Chlamydia Pathogenesis

Chlamydia trachomatis and Chlamydia pneumoniae are among the most significant bacterial pathogens afflicting humans. According to the Centers for Disease Control, C. trachomatis has the highest incidence of infection among all reported infectious diseases in the United States. Globally, it is the most prevalent sexually-transmitted bacterial disease, as well as the most-common cause of non-heritable blindness. According to serological analyses, close to 80% of the adult population has been exposed to C. pneumoniae.  C. pneumoniae infections are strongly correlated with development of atherosclerosis and heart disease, the leading cause of death in the U.S. Together, these observations highlight the extreme importance of Chlamydia infections to public health.

Despite this enormous impact on public health, surprisingly little is known about C. trachomatis and C. pneumoniae including aspects of basic biology, genetics, and pathogenesis. This is indicative of the challenges inherent to chlamydial research such as, lack of a system for directed genetic manipulation and inability to cultivate organisms axenically. However, new tools and technological advances in fields such as biochemistry, genetics/genomics, and structural biology have opened new avenues of research and facilitated our ability to understand the unique biology of this medically important bacterial pathogen.

Chlamydia are obligate intracellular bacteria maintained through a characteristic bi-phasic developmental cycle that is intimately linked with pathogenesis. This virulence defining developmental cycle is governed predominately at the transcriptional level; however, there remain critical gaps in our understanding of developmental regulatory mechanisms in Chlamydia. As such, one of the primary long-term goals of our research is to contribute to a delineation of the key molecular mechanisms that function to regulate chlamydial development and pathogenesis.

An additional challenge to understanding the biology and pathogenesis of Chlamydia is the relatively high percentage (~25-35%) of encoded proteins with unknown function. Given the absence of a system for directed genetic manipulation in Chlamydia, we have addressed this challenge by initiating a collaborative structural genomics project that enlists both computational and experimental approaches.

Antibiotic therapy is effective in treating Chlamydia infections. However, a large portion (estimates as high as 75%) of C. trachomatis infected individuals are asymptomatic and continue to be contagious. In the absence of a safe and effective vaccine, developing vaginal delivered microbicides effective against C. trachomatis infections is a high priority. Through collaborative efforts, we have initiated multiple, complimentary and cohesive projects to identify and develop vaginal delivered microbicide components that are safe and effective against C. trachomatis infections.

Selected Publications

  1. Baid S, Hefty PS, Morgan DE. A CURE for the COVID-19 Era: A Vaccine-Focused Online Immunology Laboratory. Journal of microbiology & biology education 2022;23(2)

  2. Dimond ZE, Suchland RJ, Baid S, LaBrie SD, Soules KR, Stanley J, Carrell S, Kwong F, Wang Y, Rockey DD, Hybiske K, Hefty PS. Inter-species lateral gene transfer focused on the Chlamydia plasticity zone identifies loci associated with immediate cytotoxicity and inclusion stability. Molecular microbiology 2021;116(6)

  3. Smaili FZ, Tian S, Roy A, Alazmi M, Arold ST, Mukherjee S, Hefty PS, Chen W, Gao X. QAUST: Protein Function Prediction Using Structure Similarity, Protein Interaction, and Functional Motifs. Genomics, proteomics & bioinformatics 2021;19(6)

  4. Soules, K. R.; LaBrie, S. D.; May, B. H.; Hefty, P. S., Sigma 54-Regulated Transcription Is Associated with Membrane Reorganization and Type III Secretion Effectors during Conversion to Infectious Forms of Chlamydia trachomatis. mBio 2020, 11 (5).

  5. Soules, K. R.; Dmitriev, A.; LaBrie, S. D.; Dimond, Z. E.; May, B. H.; Johnson, D. K.; Zhang, Y.; Battaile, K. P.; Lovell, S.; Hefty, P. S., Structural and ligand binding analyses of the periplasmic sensor domain of RsbU in Chlamydia trachomatis support a role in TCA cycle regulation. Mol Microbiol 2020, 113 (1), 68-88.

  6. Dimond, Z. E.; Hefty, P. S., Comprehensive genome analysis and comparisons of the swine pathogen, Chlamydia suis reveals unique ORFs and candidate host-specificity factors. Pathog Dis 2020.

  7. Wang, Y.; LaBrie, S. D.; Carrell, S. J.; Suchland, R. J.; Dimond, Z. E.; Kwong, F.; Rockey, D. D.; Hefty, P. S.; Hybiske, K., Development of Transposon Mutagenesis for Chlamydia muridarum. J Bacteriol 2019, 201 (23).

  8. Suchland, R. J.; Carrell, S. J.; Wang, Y.; Hybiske, K.; Kim, D. B.; Dimond, Z. E.; Hefty, P. S.; Rockey, D. D., Chromosomal Recombination Targets in Chlamydia Interspecies Lateral Gene Transfer. J Bacteriol 2019, 201 (23).

  9. LaBrie, S. D.; Dimond, Z. E.; Harrison, K. S.; Baid, S.; Wickstrum, J.; Suchland, R. J.; Hefty, P. S., Transposon Mutagenesis in Chlamydia trachomatis Identifies CT339 as a ComEC Homolog Important for DNA Uptake and Lateral Gene Transfer. MBio 2019, 10 (4).

  10. Cosse, M. M.; Barta, M. L.; Fisher, D. J.; Oesterlin, L. K.; Niragire, B.; Perrinet, S.; Millot, G. A.; Hefty, P. S.; Subtil, A., The Loss of Expression of a Single Type 3 Effector (CT622) Strongly Reduces Chlamydia trachomatis Infectivity and Growth. Front Cell Infect Microbiol 2018, 8, 145.

  11. Fischer, A.; Harrison, K. S.; Ramirez, Y.; Auer, D.; Chowdhury, S. R.; Prusty, B. K.; Sauer, F.; Dimond, Z.; Kisker, C.; Hefty, P. S.; Rudel, T., Chlamydia trachomatis-containing vacuole serves as deubiquitination platform to stabilize Mcl-1 and to interfere with host defense. Elife 2017, 6.

  12. Tifrea, D. F.; Barta, M. L.; Pal, S.; Hefty, P. S.; de la Maza, L. M., Computational modeling of TC0583 as a putative component of the Chlamydia muridarum V-type ATP synthase complex and assessment of its protective capabilities as a vaccine antigen. Microbes Infect 2016, 18 (4), 245-53.

  13. Brothwell, J. A.; Muramatsu, M. K.; Toh, E.; Rockey, D. D.; Putman, T. E.; Barta, M. L.; Hefty, P. S.; Suchland, R. J.; Nelson, D. E., Interrogating Genes That Mediate Chlamydia trachomatis Survival in Cell Culture Using Conditional Mutants and Recombination. J Bacteriol 2016, 198 (15), 2131-9.

  14. Kemege, K. E.; Hickey, J. M.; Barta, M. L.; Wickstrum, J.; Balwalli, N.; Lovell, S.; Battaile, K. P.; Hefty, P. S., Chlamydia trachomatis protein CT009 is a structural and functional homolog to the key morphogenesis component RodZ and interacts with division septal plane localized MreB. Mol Microbiol 2015, 95 (3), 365-82. 

  15. Barta, M. L.; Battaile, K. P.; Lovell, S.; Hefty, P. S., Hypothetical protein CT398 (CdsZ) interacts with sigma(54) (RpoN)-holoenzyme and the type III secretion export apparatus in Chlamydia trachomatis. Protein Sci 2015, 24 (10), 1617-32.

  16. Osaka, I.; Hefty, P. S., Lipopolysaccharide-binding alkylpolyamine DS-96 inhibits Chlamydia trachomatis infection by blocking attachment and entry. Antimicrob Agents Chemother 2014, 58 (6), 3245- 54.

  17. Barta, M. L.; Thomas, K.; Yuan, H.; Lovell, S.; Battaile, K. P.; Schramm, V. L.; Hefty, P. S., Structural and biochemical characterization of Chlamydia trachomatis hypothetical protein CT263 supports that menaquinone synthesis occurs through the futalosine pathway. J Biol Chem 2014, 289 (46), 32214-29.

  18. Barta, M. L.; Lovell, S.; Sinclair, A. N.; Battaile, K. P.; Hefty, P. S., Chlamydia trachomatis CT771 (nudH) is an asymmetric Ap4A hydrolase. Biochemistry 2014, 53 (1), 214-24.

  19. Barta, M. L.; Hickey, J. M.; Anbanandam, A.; Dyer, K.; Hammel, M.; Hefty, P. S., Atypical response regulator ChxR from Chlamydia trachomatis is structurally poised for DNA binding. PLoS One 2014, 9 (3), e91760.

  20. Wickstrum, J.; Sammons, L. R.; Restivo, K. N.; Hefty, P. S., Conditional gene expression in Chlamydia trachomatis using the tet system. PLoS One 2013, 8 (10), e76743.

  21. Osaka, I.; Hefty, P. S., Simple resazurin-based microplate assay for measuring Chlamydia infections. Antimicrob Agents Chemother 2013, 57 (6), 2838-40.

  22. Koppolu, V.; Osaka, I.; Skredenske, J. M.; Kettle, B.; Hefty, P. S.; Li, J.; Egan, S. M., Small- molecule inhibitor of the Shigella flexneri master virulence regulator VirF. Infect Immun 2013, 81 (11), 4220-31.

  23. Barta, M. L.; Hickey, J.; Kemege, K. E.; Lovell, S.; Battaile, K. P.; Hefty, P. S., Structure of CT584 from Chlamydia trachomatis refined to 3.05 A resolution. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013, 69 (Pt 11), 1196-201.

  24. Osaka, I.; Hills, J. M.; Kieweg, S. L.; Shinogle, H. E.; Moore, D. S.; Hefty, P. S., An automated image-based method for rapid analysis of Chlamydia infection as a tool for screening antichlamydial agents. Antimicrob Agents Chemother 2012, 56 (8), 4184-8.

  25. Kemege, K. E.; Hickey, J. M.; Lovell, S.; Battaile, K. P.; Zhang, Y.; Hefty, P. S., Ab initio structural modeling of and experimental validation for Chlamydia trachomatis protein CT296 reveal structural similarity to Fe(II) 2-oxoglutarate-dependent enzymes. J Bacteriol 2011, 193 (23), 6517-28.

  26. Hickey, J. M.; Weldon, L.; Hefty, P. S., The atypical OmpR/PhoB response regulator ChxR from Chlamydia trachomatis forms homodimers in vivo and binds a direct repeat of nucleotide sequences. J Bacteriol 2011, 193 (2), 389-98.

  27. Hickey, J. M.; Lovell, S.; Battaile, K. P.; Hu, L.; Middaugh, C. R.; Hefty, P. S., The atypical response regulator protein ChxR has structural characteristics and dimer interface interactions that are unique within the OmpR/PhoB subfamily. J Biol Chem 2011, 286 (37), 32606-16.
  28. Markham, A. P.; Jaafar, Z. A.; Kemege, K. E.; Middaugh, C. R.; Hefty, P. S., Biophysical characterization of Chlamydia trachomatis CT584 supports its potential role as a type III secretion needle tip protein. Biochemistry 2009, 48 (43), 10353-61.

  29. Hickey, J. M.; Hefty, P. S.; Lamb, A. L., Expression, purification, crystallization and preliminary X- ray analysis of the DNA-binding domain of a Chlamydia trachomatis OmpR/PhoB-subfamily response regulator homolog, ChxR. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009, 65 (Pt 8), 791-4.

  30. Abromaitis, S.; Hefty, P. S.; Stephens, R. S., Chlamydia pneumoniae encodes a functional aromatic amino acid hydroxylase. FEMS Immunol Med Microbiol 2009, 55 (2), 196-205.

  31. Hefty, P. S.; Stephens, R. S., Chlamydial type III secretion system is encoded on ten operons preceded by sigma 70-like promoter elements. J Bacteriol 2007, 189 (1), 198-206. 

  32. Koo, I. C.; Walthers, D.; Hefty, P. S.; Kenney, L. J.; Stephens, R. S., ChxR is a transcriptional activator in Chlamydia. Proc Natl Acad Sci U S A 2006, 103 (3), 750-5.

  33. Hua, L.; Hefty, P. S.; Lee, Y. J.; Lee, Y. M.; Stephens, R. S.; Price, C. W., Core of the partner switching signalling mechanism is conserved in the obligate intracellular pathogen Chlamydia trachomatis. Mol Microbiol 2006, 59 (2), 623-36.

  34. Alitalo, A.; Meri, T.; Chen, T.; Lankinen, H.; Cheng, Z. Z.; Jokiranta, T. S.; Seppala, I. J.; Lahdenne, P.; Hefty, P. S.; Akins, D. R.; Meri, S., Lysine-dependent multipoint binding of the Borrelia burgdorferi virulence factor outer surface protein E to the C terminus of factor H. J Immunol 2004, 172 (10), 6195-201.

  35. Brooks, C. S.; Hefty, P. S.; Jolliff, S. E.; Akins, D. R., Global analysis of Borrelia burgdorferi genes regulated by mammalian host-specific signals. Infect Immun 2003, 71 (6), 3371-83.

  36. Hefty, P. S.; Jolliff, S. E.; Caimano, M. J.; Wikel, S. K.; Akins, D. R., Changes in temporal and spatial patterns of outer surface lipoprotein expression generate population heterogeneity and antigenic diversity in the Lyme disease spirochete, Borrelia burgdorferi. Infect Immun 2002, 70 (7), 3468- 78.

  37. Hefty, P. S.; Brooks, C. S.; Jett, A. M.; White, G. L.; Wikel, S. K.; Kennedy, R. C.; Akins, D. R., OspE-related, OspF-related, and Elp lipoproteins are immunogenic in baboons experimentally infected with Borrelia burgdorferi and in human lyme disease patients. J Clin Microbiol 2002, 40 (11), 4256-65.

  38. Alitalo, A.; Meri, T.; Lankinen, H.; Seppala, I.; Lahdenne, P.; Hefty, P. S.; Akins, D.; Meri, S., Complement inhibitor factor H binding to Lyme disease spirochetes is mediated by inducible expression of multiple plasmid-encoded outer surface protein E paralogs. J Immunol 2002, 169 (7), 3847-53.

  39. Hefty, P. S.; Jolliff, S. E.; Caimano, M. J.; Wikel, S. K.; Radolf, J. D.; Akins, D. R., Regulation of OspE-related, OspF-related, and Elp lipoproteins of Borrelia burgdorferi strain 297 by mammalian host-specific signals. Infect Immun 2001, 69 (6), 3618-27.

  40. Watts, A. M.; Stanley, J. R.; Shearer, M. H.; Hefty, P. S.; Kennedy, R. C., Fetal immunization of baboons induces a fetal-specific antibody response. Nat Med 1999, 5 (4), 427-30.

  41. Hefty, P. S.; Kennedy, R. C., Immunoglobulin variable regions as idiotype vaccines. Infect Dis Clin North Am 1999, 13 (1), 27-37, vi.