Prof. Dr. Ulla Bonas (PI)

The role of small proteins in the plant pathogen Xanthomonas

Martin-Luther-Universität Halle-Wittenberg (Germany), Institute for Biology, Department of Genetics

Prof. Dr. Ulla Bonas and Dr. Cornelius Schmidtke

Gamma-proteobacteria of the genus Xanthomonas cause economically important diseases in crop plants. Our model system to elucidate bacteria-plant interactions is X. campestris pv. vesicatoria (Xcv), which causes bacterial spot disease on pepper and tomato (Thieme et al., 2005). Pathogenicity of Xcv depends on a type III secretion (T3S) system and the translocation of type III effector proteins into plant cells. Effector proteins interfere with host cellular pathways and ultimately enable bacterial multiplication in the plant tissue (Adlung et al., 2016). In addition, small regulatory RNAs and extracellular enzymes contribute to Xcv virulence (Szczesny et al., 2010; Schmidtke et al., 2012, 2013). Recent RNA-seq analyses revealed that the protein-coding potential of the Xcv genome might have been underestimated: more than 200 transcripts contain one or several small open reading frames (sORFs), which potentially encode small proteins with a size of less than 50 amino acids (Schmidtke et al., 2012 and unpublished data). About 25% of the sORF-containing transcripts are co-regulated with the T3S system. Several sORFs appears to be conserved and genetically associated with known virulence genes in Xcv and other pathogenic Xanthomonas spp. Thus, we assume important roles of small proteins in the Xcv-plant interaction.

We aim at (i) the identification of translated sORFs and corresponding small proteins in Xcv, (ii) the identification of small proteins that are secreted or translocated into host cells, (iii) the functional characterization of selected small proteins with respect to their role in Xcv virulence and interaction partners.

  1. Adlung, N., Prochaska, H., Thieme, S., Banik, A., Blüher, D., John, P., Nagel, O., Schulze, S., Gantner, J., Delker, C. et al. (2016) Non-host Resistance Induced by the Xanthomonas Effector XopQ Is Widespread within the Genus Nicotiana and Functionally Depends on EDS1. Front Plant Sci, 7, 1796.
  2. Schmidtke, C., Findeiß, S., Sharma, C.M., Kuhfuss, J., Hoffmann, S., Vogel, J., Stadler, P.F. and Bonas, U. (2012) Genome-wide transcriptome analysis of the plant pathogen Xanthomonas identifies sRNAs with putative virulence functions. Nucleic Acids Res., 40, 2020-2031.
  3. Schmidtke, C., Abendroth, U., Brock, J., Serrania, J., Becker, A. and Bonas, U. (2013) Small RNA sX13: a multifaceted regulator of virulence in the plant pathogen Xanthomonas. PLoS Pathog., 9, e1003626.
  4. Szczesny, R., Jordan, M., Schramm, C., Schulz, S., Cogez, V., Bonas, U. and Büttner, D. (2010) Functional characterization of the Xcs and Xps type II secretion systems from the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria. New Phytol., 187, 983-1002.
  5. Thieme, F., Koebnik, R., Bekel, T., Berger, C., Boch, J., Büttner, D., Caldana, C., Gaigalat, L., Goesmann, A., Kay, S. et al. (2005) Insights into genome plasticity and pathogenicity of the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria revealed by the complete genome sequence. J Bacteriol, 187, 7254-7266.