The Transcriptional Activator LdtR from ‘ Liberibacter asiaticus’ Mediates Osmotic Stress Tolerance

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The rapid expansion of Huanglongbing disease (HLB) has caused a severe crisis in the citrus industry, with no solution visible in the near future. The causative agent, ‘Candidatus Liberibacter asiaticus’, is an unculturable bacterium under common laboratory conditions, which has made it difficult to gain understanding of this pathogen. Here we used a biochemical approach to identify new chemicals that could be used for the treatment of this devastating disease. These chemicals target a specific transcription factor (LdtR) in ‘Ca. Liberibacter asiaticus’. When bound to LdtR, the chemicals inactivate the protein, which disrupts a cell wall remodeling process that is critical for survival of the pathogen when exposed to osmotic stress (i.e. within the phloem of a citrus tree). Several model strains were used to confirm that the newly identified transcription factor (LdtR) and its regulated genes (ldtR and ldtP) confer tolerance to osmotic stress. The results presented in this study provide strong proof of concept for the use of small molecules that target LdtR, as a potential treatment option for Huanglongbing disease.

Vyšlo v časopise: The Transcriptional Activator LdtR from ‘ Liberibacter asiaticus’ Mediates Osmotic Stress Tolerance. PLoS Pathog 10(4): e32767. doi:10.1371/journal.ppat.1004101
Kategorie: Research Article
prolekare.web.journal.doi_sk: https://doi.org/10.1371/journal.ppat.1004101

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Zdroje

1. ZhangM, Powell Ca, ZhouL, HeZ, StoverE, et al. (2011) Chemical compounds effective against the citrus Huanglongbing bacterium “Candidatus Liberibacter asiaticus” in planta. Phytopathology 101 : 1097–1103.

2. HoffmanMT, DoudMS, WilliamsL, ZhangM-Q, DingF, et al. (2013) Heat treatment eliminates “Candidatus Liberibacter asiaticus” from infected citrus trees under controlled conditions. Phytopathology 103 : 15–22.

3. BishopJL, BoyleEC, FinlayBB (2007) Deception point: peptidoglycan modification as a means of immune evasion. Proceedings of the National Academy of Sciences of the United States of America 104 : 691–692.

4. DavisKM, WeiserJN (2011) Modifications to the peptidoglycan backbone help bacteria to establish infection. Infection and immunity 79 : 562–570.

5. ErbsG, NewmanM (2012) The role of lipopolysaccharide and peptidoglycan, two glycosylated bacterial microbe-associated molecular patterns (MAMPs), in plant innate immunity. Mol Plant Pathol 13 : 95–104 doi:10.1111/J.1364-3703.2011.00730.X

6. BrownPJB, de PedroMA, KyselaDT, Van der HenstC, KimJ, et al. (2012) Polar growth in the Alphaproteobacterial order Rhizobiales. Proceedings of the National Academy of Sciences of the United States of America 109 : 1697–1701.

7. ChauhanS, O'BrianMR (1993) Bradyrhizobium japonicum delta-aminolevulinic acid dehydratase is essential for symbiosis with soybean and contains a novel metal-binding domain. Journal of bacteriology 175 : 7222–7227.

8. CavaF, de PedroMa, LamH, DavisBM, WaldorMK (2011) Distinct pathways for modification of the bacterial cell wall by non-canonical D-amino acids. The EMBO journal 30 : 3442–3453.

9. KovachME, ElzerPH, HillDS, RobertsonGT, FarrisMa, et al. (1995) Four new derivatives of the broad-host-range cloning vector pBBR1MCS, carrying different antibiotic-resistance cassettes. Gene 166 : 175–176.

10. PagliaiFa, GardnerCL, PandeSG, LorcaGL (2010) LVIS553 transcriptional regulator specifically recognizes novobiocin as an effector molecule. The Journal of biological chemistry 285 : 16921–16930.

11. VedadiM, NiesenFH, Allali-HassaniA, FedorovOY, FinertyPJ, et al. (2006) Chemical screening methods to identify ligands that promote protein stability, protein crystallization, and structure determination. Proceedings of the National Academy of Sciences of the United States of America 103 : 15835–15840.

12. LorcaGL, EzerskyA, LuninVV, WalkerJR, AltamentovaS, et al. (2007) Glyoxylate and pyruvate are antagonistic effectors of the Escherichia coli IclR transcriptional regulator. The Journal of biological chemistry 282 : 16476–16491.

13. LeonardMT, FagenJR, Davis-RichardsonAG, DavisMJ, TriplettEW (2012) Complete genome sequence of Liberibacter crescens BT-1. Standards in genomic sciences 7 : 271–283.

14. FolimonovaSY, AchorDS (2010) Early events of citrus greening (Huanglongbing) disease development at the ultrastructural level. Phytopathology 100 : 949–958.

15. AuclairJL (1963) Aphid Feeding and Nutrition. Annual Review of Entomology 8 : 439–490.

16. Moorby J (1981) Transport Systems in Plants. London; New York: Longman.

17. LavollayM, ArthurM, FourgeaudM, DubostL, MarieA, et al. (2008) The peptidoglycan of stationary-phase Mycobacterium tuberculosis predominantly contains cross-links generated by L,D-transpeptidation. Journal of bacteriology 190 : 4360–4366.

18. LamH, OhD, CavaF, TakacsCN, ClardyJ, et al. (2010) D-amino acids govern stationary phase cell wall remodeling in bacteria. NIH Public Access. Science 325 : 1552–1555 doi:10.1126/science.1178123.D-amino

19. BettsJC, LukeyPT, RobbLC, McAdamRa, DuncanK (2002) Evaluation of a nutrient starvation model of Mycobacterium tuberculosis persistence by gene and protein expression profiling. Molecular microbiology 43 : 717–731.

20. YanQ, SreedharanA, WeiS, WangJ, Pelz-StelinskiK, et al. (2013) Global gene expression changes in Candidatus Liberibacter asiaticus during the transmission in distinct hosts between plant and insect. Molecular plant pathology 14 : 391–404.

21. BaumgarthB, BartelsFW, AnselmettiD, BeckerA, RosR (2005) Detailed studies of the binding mechanism of the Sinorhizobium meliloti transcriptional activator ExpG to DNA. Microbiology 151 : 259–268.

22. ZhuD, WangY, ZhangM, IkedaH, DengZ, et al. (2013) Product-mediated regulation of pentalenolactone biosynthesis in Streptomyces species by the MarR/SlyA family activators PenR and PntR. Journal of bacteriology 195 : 1255–1266.

23. BartelsFW, BaumgarthB, AnselmettiD, RosR, BeckerA (2003) Specific binding of the regulatory protein ExpG to promoter regions of the galactoglucan biosynthesis gene cluster of Sinorhizobium meliloti -⁠ a combined molecular biology and force spectroscopy investigation. Journal of Structural Biology 143 : 145–152.

24. HammesW, SchleiferKH, KandlerO (1973) Mode of action of glycine on the biosynthesis of peptidoglycan. Journal of bacteriology 116 : 1029–1053.

25. VanderlindeEM, YostCK (2012) Mutation of the sensor kinase chvG in Rhizobium leguminosarum negatively impacts cellular metabolism, outer membrane stability, and symbiosis. Journal of bacteriology 194 : 768–777.

26. SkinnerFA (1977) An Evaluation of the Nile Blue Test for Differentiating Rhizobia from Agrobacteria. Journal of Applied Bacteriology 43 : 91–98.

27. DubéeV, TribouletS, MainardiJ-L, Ethève-QuelquejeuM, GutmannL, et al. (2012) Inactivation of Mycobacterium tuberculosis l,d-transpeptidase LdtMt1 by carbapenems and cephalosporins. Antimicrobial agents and chemotherapy 56 : 4189–4195.

28. SambrookJ (2008) Molecular Cloning.

29. NiesenFH, BerglundH, VedadiM (2007) The use of differential scanning fluorimetry to detect ligand interactions that promote protein stability. Nature protocols 2 : 2212–2221.

30. ZianniM, TessanneK, MerighiM, LagunaR, TabitaFR (2006) Ab r f. 17 : 103–113.

31. Guérout-FleuryaM, FrandsenN, StragierP (1996) Plasmids for ectopic integration in Bacillus subtilis. Gene 180 : 57–61.

32. Petit-GlatronMF, ChambertR (1992) Peptide carrier potentiality of Bacillus subtilis levansucrase. Journal of general microbiology 138 : 1089–1095.

33. Miller JH (1972) Experiments in Molecular Genetics. Cold Springs Harbor (New York): Cold Spring Harbor Laboratory Press.

34. GaoM, ChenH, EberhardA, GronquistR, RobinsonJB, et al. (2005) sinI -⁠ and expR -Dependent Quorum Sensing in Sinorhizobium meliloti sinI -⁠ and expR-Dependent Quorum Sensing in Sinorhizobium meliloti †. J Bacteriol 187 : 7931–7944 doi:10.1128/JB.187.23.7931

35. OkeV, LongSR (1999) Bacterial genes induced within the nodule during the Rhizobium-legume symbiosis. Molecular microbiology 32 : 837–849.

36. FinanTM, KunkelB, De VosGF, SignerER (1986) Second symbiotic megaplasmid in Rhizobium meliloti carrying exopolysaccharide and thiamine synthesis genes. Journal of bacteriology 167 : 66–72.

37. HartungJS, PaulC, AchorD, BrlanskyRH (2010) Colonization of dodder, Cuscuta indecora, by “Candidatus Liberibacter asiaticus” and “Ca. L. americanus”. Phytopathology 100 : 756–762.

38. LiW, HartungJS, LevyL (2006) Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing. Journal of microbiological methods 66 : 104–115.

39. HilfME, SimsKR, FolimonovaSY, AchorDS (2013) Visualization of “Candidatus Liberibacter asiaticus” cells in the vascular bundle of citrus seed coats with fluorescence in situ hybridization and transmission electron microscopy. Phytopathology 103 : 545–554.

40. Pelz-StelinskiKS, BrlanskyRH, EbertTa, RogersME (2010) Transmission Parameters for Candidatus Liberibacter asiaticus by Asian Citrus Psyllid (Hemiptera: Psyllidae). Journal of Economic Entomology 103 : 1531–1541.

41. GalibertF, FinanTM, LongSR, PuhlerA, AbolaP, et al. (2001) The composite genome of the legume symbiont Sinorhizobium meliloti. Science 293 : 668–672 Available: http://www.ncbi.nlm.nih.gov/pubmed/11474104. Accessed 24 January 2014.

42. GaoM, ChenH, EberhardA, GronquistMR, RobinsonJB, et al. (2005) sinI -⁠ and expR-dependent quorum sensing in Sinorhizobium meliloti. Journal of bacteriology 187 : 7931–7944.