PMID:25461800

Citation	Komi, KK, Ge, YM, Xin, XY, Ojcius, DM, Sun, D, Hu, WL, Zhao, X, Lin, X and Yan, J (2015) ChpK and MazF of the toxin-antitoxin modules are involved in the virulence of Leptospira interrogans during infection. Microbes Infect. 17:34-47
Abstract	Pathogenic Leptospira species are the causative agents of leptospirosis, a global zoonotic infectious disease. Toxin-antitoxin (TA) modules have been confirmed as stress-response elements that induce prokaryotic and eukaryotic cell-growth arrest or death, but their role in the virulence of Leptospira has not been reported. Here, we confirmed that all the tested leptospiral strains had the chpIK and mazEF TA modules with highly-conserved sequences. The transcription and expression of the chpI, chpK, mazE, and mazF genes of Leptospira interrogans strain Lai were significantly increased during infection of phorbol 12-myristate 13-acetate-induced human THP-1 macrophages. The toxic ChpK and MazF but not the antitoxic ChpI and MazE proteins were detectable in the cytoplasmic fraction of leptospire-infected THP-1 cells, indicating the external secretion of ChpK and MazF during infection. Transfection of the chpK or mazF gene caused decreased viability and necrosis in THP-1 cells, whereas the chpI or mazE gene transfection did not affect the viability of THP-1 cells but blocked the ChpK or MazF-induced toxicity. Deletion of the chpK or mazF gene also decreased the late-apoptotic and/or necrotic ratios of THP-1 cells at the late stages of infection. The recombinant protein MazF (rMazF) cleaved the RNAs but not the DNAs from Leptospira and THP-1 cells, and this RNA cleavage was blocked by rMazE. However, the rChpK had no RNA or DNA-degrading activity. All these findings indicate that the ChpK and MazF proteins in TA modules are involved in the virulence of L. interrogans during infection.
Links	PubMed Online version:10.1016/j.micinf.2014.10.010
Keywords	Apoptosis; Bacterial Proteins; Bacterial Toxins/genetics; Bacterial Toxins/metabolism; Cell Line; Cell Survival; Cytoplasm/chemistry; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Gene Deletion; Gene Expression Profiling; Humans; Leptospira interrogans/genetics; Leptospira interrogans/growth & development; Leptospira interrogans/pathogenicity; Macrophages/microbiology; Macrophages/physiology; Transfection; Virulence
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LEPBJ:Q04VF3		GO:0008284: positive regulation of cell population proliferation	ECO:0001258:		P		Fig. 1B shows that mazE (an anti-toxin) rescues the expression of cells expressing only the mazF toxin in Leptospira interrogans.	complete CACAO 13591
LEPIR:A0A0C5XAD8		GO:0110001: toxin-antitoxin complex	ECO:0001258:		C		Figure 1.B shows that MazF, a protein from Leptospira interrogans, kills the cell when produced alone, but complexes with MazE to repress itself.	complete
LEPIR:Q93MT8		GO:0110001: toxin-antitoxin complex	ECO:0001258:		C		Figure 1B show growth curves, in which OD600 reflect the number of E. coli in cultures incubated. ChpK, also called mRNA interferase, is a toxin in Leptospira interrogans that allows increase in OD600 as long as its expressed alongside the antoxin ChpI that neutralizes the toxin. If ChpK is expressed without the ChpI, the toxicity of ChpK will cause the OD600 value to decrease.	complete CACAO 13598
LEPIR:Q93MT8		GO:0001907: killing by symbiont of host cells	ECO:0005034:		P		Fig. 3 shows that ChpK from Leptospira interrogans is involved in inducing necrotic death of the THP-1 host cell.	complete CACAO 13641
LEPIR:Q93MT9		GO:0110001: toxin-antitoxin complex	ECO:0001258:		C		Figure 1B show growth curves, in which OD600 reflect the number of E. coli in cultures incubated. ChpI is a antitoxin in Leptospira interrogans that allows increase in OD600 if by itself or if its expressed alongside the toxin ChpK, in which case it neutralizes the toxin.	complete CACAO 13601
LEPIN:G1UB28		GO:0004540: ribonuclease activity	ECO:0005653:		F		Fig. 5 shows that mazF (a toxin) found in Leptospira interrogans degrades RNA.	complete CACAO 13616
LEPIN:G1UB28		GO:0001907: killing by symbiont of host cells	ECO:0005034:		P		Fig. 3 shows that MazF (aka LA_2843) from Leptospira interrogans is involved in inducing necrotic death of the THP-1 host cell.	complete CACAO 13640

References

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