Legionella pneumophila (Lp) is the agent of Legionnaires' disease pneumonia. In its aquatic habitat, Lp survives as an intracellular parasite of protozoans, and after inoculation into the lung, it flourishes within alveolar macrophages. Previously, we discovered an Lp gene (pilD) whose product is homologous with PilD, which, in other Gram-negatives, mediates pilus biogenesis and type II protein secretion. Indeed, an Lp pilD mutant lacked pili. More importantly, the pilD mutant, but not a pilin mutant, was defective for infection of amoebae and macrophages, suggesting that Lp has a type II secretion system that promotes infection. During this last grant period, we confirmed Lp has a type II system (lsp) that mediates secretion of many proteins, including novel enzymes, and is critical for infection of both protozoa and human cells. Some of our other data suggested that the Lp peptidyl-prolyl isomerase Mip and SurA have a role in the secretion process. Presently, Lp is the only known system for studying type II secretion in an intracellular pathogen. In the last grant period, we also demonstrated that lsp mutants are greatly impaired for survival in the lungs of A/J mice, with the severity of their defect indicating that Lp type II secretion is a key virulence determinant that may be involved in more than just macrophage infection. Finally, we made the novel observation that lsp is required for growth at 12-25 degrees C. Thus, Lp type II secretion is uniquely critical for intracellular infection, virulence, and low-temperature growth. In the current proposal, we aim to identify the type II exoproteins that are critical for intracellular infection, confirm the role of Mip and SurA in secretion, and determine how type II secretion promotes in vivo survival as well as low-temperature growth in water and amoebae. The results of these studies will i) increase our understanding of Lp physiology and pathogenesis, ii) provide new insight into bacterial protein secretion, intracellular infection, and low-temperature growth, and iii) have implications for other important human pathogens, including both other intracellular parasites and extracellular pathogens, such as Vibrio, Pseudomonas, and Burkholderia that survive at low-temperature and have type II systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI043987-08
Application #
6985385
Study Section
Special Emphasis Panel (ZRG1-BM-1 (01))
Program Officer
Korpela, Jukka K
Project Start
1998-12-01
Project End
2008-11-30
Budget Start
2005-12-01
Budget End
2006-11-30
Support Year
8
Fiscal Year
2006
Total Cost
$251,400
Indirect Cost
Name
Northwestern University at Chicago
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
White, Richard C; Gunderson, Felizza F; Tyson, Jessica Y et al. (2018) Type II Secretion-Dependent Aminopeptidase LapA and Acyltransferase PlaC Are Redundant for Nutrient Acquisition during Legionella pneumophila Intracellular Infection of Amoebas. MBio 9:
Mallama, Celeste A; McCoy-Simandle, Kessler; Cianciotto, Nicholas P (2017) The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages. Infect Immun 85:
Cianciotto, Nicholas P; White, Richard C (2017) Expanding Role of Type II Secretion in Bacterial Pathogenesis and Beyond. Infect Immun 85:
Truchan, Hilary K; Christman, Harry D; White, Richard C et al. (2017) Type II Secretion Substrates of Legionella pneumophila Translocate Out of the Pathogen-Occupied Vacuole via a Semipermeable Membrane. MBio 8:
White, Richard C; Cianciotto, Nicholas P (2016) Type II Secretion Is Necessary for Optimal Association of the Legionella-Containing Vacuole with Macrophage Rab1B but Enhances Intracellular Replication Mainly by Rab1B-Independent Mechanisms. Infect Immun 84:3313-3327
DuMont, Ashley L; Karaba, Sara M; Cianciotto, Nicholas P (2015) Type II Secretion-Dependent Degradative and Cytotoxic Activities Mediated by Stenotrophomonas maltophilia Serine Proteases StmPr1 and StmPr2. Infect Immun 83:3825-37
Tyson, Jessica Y; Vargas, Paloma; Cianciotto, Nicholas P (2014) The novel Legionella pneumophila type II secretion substrate NttC contributes to infection of amoebae Hartmannella vermiformis and Willaertia magna. Microbiology 160:2732-44
Karaba, Sara M; White, Richard C; Cianciotto, Nicholas P (2013) Stenotrophomonas maltophilia encodes a type II protein secretion system that promotes detrimental effects on lung epithelial cells. Infect Immun 81:3210-9
Gunderson, Felizza F; Cianciotto, Nicholas P (2013) The CRISPR-associated gene cas2 of Legionella pneumophila is required for intracellular infection of amoebae. MBio 4:e00074-13
Cianciotto, Nicholas P (2013) Type II secretion and Legionella virulence. Curr Top Microbiol Immunol 376:81-102

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