The xylan utilization system of the plant pathogen Xanthomonas campestris pv campestris controls epiphytic life and reveals common features with oligotrophic bacteria and animal gut symbionts

Guillaume Dejean (1) , Servane Blanvillain-Baufume (1, 1) , Alice Boulanger (1) , Armelle Darrasse (2) , Thomas Duge de Bernonville (1) , Anne-Laure Girard (2) , Sebastien Carrere (1) , Stevie Jamet (1) , Claudine Zischek (1) , Martine Lautier (1, 3) , Magali Sole , Daniela Buettner , Marie Agnes Jacques (2) , Emmanuelle Lauber (1) , Matthieu Arlat (1, 3)

1 LIPM - Laboratoire des interactions plantes micro-organismes
2 IRHS - Institut de Recherche en Horticulture et Semences
3 UT3 - Université Toulouse III - Paul Sabatier

Xylan is a major structural component of plant cell wall and the second most abundant plant polysaccharide in nature. Here, by combining genomic and functional analyses, we provide a comprehensive picture of xylan utilization by Xanthomonas campestris pv campestris (Xcc) and highlight its role in the adaptation of this epiphytic phytopathogen to the phyllosphere. The xylanolytic activity of Xcc depends on xylan-deconstruction enzymes but also on transporters, including two TonB-dependent outer membrane transporters (TBDTs) which belong to operons necessary for efficient growth in the presence of xylo-oligosaccharides and for optimal survival on plant leaves. Genes of this xylan utilization system are specifically induced by xylo-oligosaccharides and repressed by a LacI-family regulator named XylR. Part of the xylanolytic machinery of Xcc, including TBDT genes, displays a high degree of conservation with the xylose-regulon of the oligotrophic aquatic bacterium Caulobacter crescentus. Moreover, it shares common features, including the presence of TBDTs, with the xylan utilization systems of Bacteroides ovatus and Prevotella bryantii, two gut symbionts. These similarities and our results support an important role for TBDTs and xylan utilization systems for bacterial adaptation in the phyllosphere, oligotrophic environments and animal guts.

Mots clés: epiphytic; gut symbiont; oligotrophy; TonB-dependent transporter; transport; xylan; xylanase; UTILIZATION GENE-CLUSTER; GRAM-NEGATIVE BACTERIA; D-XYLOSE METABOLISM; CAULOBACTER-CRESCENTUS; ESCHERICHIA-COLI; FUNCTIONAL-CHARACTERIZATION; ERWINIA-CHRYSANTHEMI; PREVOTELLA-BRYANTII; DEPENDENT TRANSPORT; BIOFILM FORMATION

Domaines: Sciences du Vivant [q-bio]

Guillaume Dejean, Servane Blanvillain-Baufume, Alice Boulanger, Armelle Darrasse, Thomas Duge de Bernonville, et al.. The xylan utilization system of the plant pathogen Xanthomonas campestris pv campestris controls epiphytic life and reveals common features with oligotrophic bacteria and animal gut symbionts. New Phytologist, 2013, 198 (3), pp.899 - 915. ⟨10.1111/nph.12187⟩. ⟨hal-01209910⟩