C.L.asiaticus

Analysis of Candidatus Liberibacter asiaticus Proteome

Qian Cong and Nick V. Grishin

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Candidatus Liberibacter asiaticus (C. L. asiaticus) is a Gram negative bacterium and is the pathogen of Citrus greening (also called huanglongbing). The ranking Candidatus is assigned to this bacterium because it cannot be maintained in bacterial culture. In nature, the bacteria utilize piercing-sucking insects, psyllid, as vectors and thus are transmitted among plants. Hosts of C. L. asiaticus include nearly all citrus species. In the plant, C. L. asiaticus resides exclusively in the phloem tissues and gradually chokes off the supply of nutrients throughout the plant, weakening the plant and eventually killing it. [1][2]

Researchers have been making effort to understand the mechanism of the disease [3][4][5] and to save citrus industry against the horrible disease [6][7]. However, difficulty in obtaining bacteria culture make it challenging to carry out experiments on C. L. Candidatus. Last year, the complete genome sequence [8] of C. L. asiaticus was obtained by Yongping Duan and his colleagues and careful analysis of the genome will provide insight into the pathogen and lead to development of methods to control the bacterium.

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Fig.1 Trees show the symptoms of Huanglongbing has yellow shoot.(Photo courtesy T.R. Gottwald and S.M. Garnsey) Fig.2 Symptoms of citrus greening on mandarin orange fruit.(Photo courtesy T.R. Gottwald and S.M. Garnsey) Fig.3 Asian citrus psyllid, Diaphorina citri Kuwayama.(Image:David Hall, USDA-ARS, Ft. Pierce , FL)

In this website, we present our results of structure and function prediction on the proteome of C. L. asiaticus. For each protein, we gathered important information from various sources, predicted local sequence features, analyzed the domain achietecture, provided structure models and predicted the function based on its relationship to known protein and protein family. All the predictions were obtained by applying multiple automatic programs followed by manually curation of the results. More importantly, we identified several virulence factors of this bacteria. This website may help us to understand the physiology of the bacteria and the mechanism of citrus greening and serve as a reference for further experimental study on the bacteria and the disease.

Description of the Database Protein Categories BLAST search the proteome

References:

[1] Bove JM, Ayres AJ. Etiology of three recent diseases of citrus in Sao Paulo State: sudden death, variegated chlorosis and huanglongbing. IUBMB Life. 2007 Apr-May;59(4-5):346-54. Review. PubMed PMID: 17505974.

[2] Gottwald TR. Current Epidemiological Understanding of Citrus Huanglongbing. Annu Rev Phytopathol. 2010 Apr 23. [Epub ahead of print] PubMed PMID: 20415578.

[3] Kim JS, Sagaram US, Burns JK, Li JL, Wang N. Response of sweet orange (Citrus sinensis) to 'Candidatus Liberibacter asiaticus' infection: microscopy and microarray analyses. Phytopathology. 2009 Jan;99(1):50-7. PubMed PMID: 19055434.

[4] Cevallos-Cevallos JM, Rouseff R, Reyes-De-Corcuera JI. Untargeted metabolite analysis of healthy and Huanglongbing-infected orange leaves by CE-DAD. Electrophoresis. 2009 Apr;30(7):1240-7. PubMed PMID: 19283697.

[5] Trivedi P, Duan Y, Wang N. Huanglongbing, a systemic disease, restructures the bacterial community associated with citrus roots. Appl Environ Microbiol. 2010 Jun;76(11):3427-36. Epub 2010 Apr 9. PubMed PMID: 20382817.

[6] Ding F, Jin S, Hong N, Zhong Y, Cao Q, Yi G, Wang G. Vitrification-cryopreservation, an efficient method for eliminating Candidatus Liberobacter asiaticus, the citrus Huanglongbing pathogen, from in vitro adult shoot tips. Plant Cell Rep. 2008 Feb;27(2):241-50. Epub 2007 Oct 23. PubMed PMID: 17955244.

[7] Vahling CM, Duan Y, Lin H. Characterization of an ATP translocase identified in the destructive plant pathogen "Candidatus Liberibacter asiaticus". J Bacteriol. 2010 Feb;192(3):834-40. Epub 2009 Nov 30. PubMed PMID: 19948801.

[8] Duan Y, Zhou L, Hall DG, Li W, Doddapaneni H, Lin H, Liu L, Vahling CM, Gabriel DW, Williams KP, Dickerman A, Sun Y, Gottwald T. Complete genome sequence of citrus huanglongbing bacterium, 'Candidatus Liberibacter asiaticus' obtained through metagenomics. Mol Plant Microbe Interact. 2009 Aug;22(8):1011-20. PubMed PMID: 19589076.