The Protease Locus of Francisella tularensis LVS Is Required for Stress Tolerance and Infection in the Mammalian Host
Abstract
Francisella tularensis is the causative agent of tularemia and a category A potential agent of bioterrorism, but the pathogenic mechanisms of F. tularensis are largely unknown. Our previous transposon mutagenesis screen identified 95 lung infectivity-associated F. tularensis genes, including those encoding the Lon and ClpP proteases. The present study validates the importance of Lon and ClpP in intramacrophage growth and infection of the mammalian host by using unmarked deletion mutants of the F. tularensis live vaccine strain (LVS). Further experiments revealed that lon and clpP are also required for F. tularensis tolerance to stressful conditions. A quantitative proteomic comparison between heat-stressed LVS and the isogenic Lon-deficient mutant identified 29 putative Lon substrate proteins. The follow-up protein degradation experiments identified five substrates of the F. tularensis Lon protease (FTL578, FTL663, FTL1217, FTL1228, and FTL1957). FTL578 (ornithine cyclodeaminase), FTL663 (heat shock protein), and FTL1228 (iron-sulfur activator complex subunit SufD) have been previously described as virulence-associated factors in F. tularensis . Identification of these Lon substrates has thus provided important clues for further understanding of the F. tularensis stress response and pathogenesis. The high-throughput approach developed in this study can be used for systematic identification of the Lon substrates in other prokaryotic and eukaryotic organisms.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2016
- Source ID
- 10.1128/iai.00076-16
Entities
People
- Haiteng Deng
- Jing-ren Zhang
- Karsten R O Hazlett
- Lihong He
- Manoj Kumar Mohan Nair
- Mengyun Zhang
- Xue Liu
- Yuling Chen
Organizations
- Albany Medical College
- Ministry of Education of the People's Republic of China
- Ministry of Science and Technology of the People's Republic of China
- National Institutes of Health
- National Natural Science Foundation of China
- Sichuan University
- Tsinghua University
- United States Department of Defense