sRNA-Xcc1

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sRNA-Xcc1 (small RNA identified from Xanthomonas campestris pv. campestris) is a family of trans-acting non-coding RNA (also known as small RNA)[1]. Homologs of sRNA-Xcc1 are found in a few bacterial strains belonging to alpha-proteobacteria,beta-proteobacteria, gamma-proteobacteria,and delta-proteobacteria. In Xanthomonas campestris pv. campestris, sRNA-Xcc1 is encoded by a integron gene cassette and is under the positive control of the virulence regulators HrpG and HrpX[2] [3].

The Origin and Phylogenetic Distribution

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sRNA-Xcc1 is encoded by a gene cassette in the integron of Xanthomonas campestris pv. campestris and homologs of sRNA-Xcc1 are frequently found in integron gene cassettes cloned from uncultured bacterium[4], it is possible that sRNA-Xcc1 is originally captured by integrons from natural environments. sRNA-Xcc1 homologs are found in a few taxonomically far related strains across alpha-, beta- and gamma-proteobacteria but not in close related bacteria, implying that sRNA-Xcc1 is transferred via horizontal gene transfer (HGT). sRNA-Xcc1 homologous gene are found located on Tn5542, a transposon carryed by the plasmid pHMT112 indicating that the horizontal transfer of sRNA-Xcc1 is realized by means of transposons and/or plasmids[5].

Potential Biological Function

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The expression of sRNA-Xcc1 is under the positive control of the two important virulence regulators HrpG and HrpX of Xanthomonas campestris pv. campestris, indicating that sRNA-Xcc1 may be involved in the pathogenesis of the pathogen.


References

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[1]Chen XL, Tang DJ, Jiang RP, He YQ, Jiang BL, Lu GT, Tang JL (2010). sRNA-Xcc1, an integron-captured transposons and/or plasmid-transferred trans-acting sRNA, is under the positive control of the key virulence regulators HrpG and HrpX of Xanthomonas campestris pathovar campestris. RNA Biology. MS in preparation.

[2] Wengelnik KG, Van den Ackerveken, Bonas U. HrpG, a key hrp regulatory protein of Xanthomonas campestris pv. vesicatoria is homologous to two-component response regulators. Mol. Plant Microbe Interact 1996; 9:704-12.

[3]Wengelnik K, Bonas, U. HrpXv, an AraC-type regulator, activates expression of five of the six loci in the hrp cluster of Xanthomonas campestris pv. vesicatoria. J. Bacteriol 1996; 178:3462-9.

[4]Gillings MR, Holley MP, Stokes HW, Holmes AJ. Integrons in Xanthomonas: a source of species genome diversity. Proc Natl Acad Sci U S A 2005; 102:4419-24.

[5]Tan HM, Tang HY, Joannou CL, Abdel-Wahab NH, Mason JR. The Pseudomonas putida ML2 plasmid-encoded genes for benzene dioxygenase are unusual in codon usage and low in G+C content. Gene 1993; 130:33-9.