THE TIGHT-ADHESION PROTEIN TadG OF BRADYRHIZOBIUM JAPONICUM IS INVOLVED IN ADHESION AND INFECTIVITY ON SOYBEAN ROOTS

MONGIARDINI, E.J.; PARISI, G.; PÉREZ GIMÉNEZ, J.; LODEIRO, A.R.

Perth

Congreso; Rhizosphere 3; 2011

Aims and BackgroundAdhesion of Bradyrhizobium japonicum to soybean roots is required for rhizosphere colonization and root infection, and is mediated by bacterial adhesins. Among them are  Tad (t ight adhesion) proteins, w hich were studied in other bacteria but not in rhizobia. We addressed a bioinformatic and molecular study of tadG in B. japonicum USDA 110.MethodsE volutionary analysis was done with PHYLIP.  Three-dimensional models were constructed with SOPMA, PredictProtein, JUFO, MODELLER, and  ITASSER.  tadG was deleted in USDA 110 by replac ement with  a  kanamycin-resistance  cassette.  Adhesion  and  infectivity  were studied  as described (1).ResultsThe ORF blr3941 encodes TadG, which is  implicated in the processing and transporting of  Flppili. TadG has N-terminal and C-terminal domains separated by a 15-aminoacid transmembrane region.  The  C-terminal  domain  is  homologous  to  integrin  α1β1 family,  and  contains  a  von Willebrand fold, w hich is related w ith cell adhesion and recognition. B. japonicum USDA 110 and the blr3941 deletion mutant adhered to roots in clusters of 4-7 cells but adhesion of mutant w as 50% lower. Accordingly, mutant infectivity diminished by 67%. ConclusionThe ORF blr3941 encodes TadG, which is  inv olved in B. japonicum  adhesion and infectivity on soybean roots.