The Type 3 Protein Secretion System of Cupriavidus taiwanensis Strain LMG19424 Compromises Symbiosis with Leucaena leucocephala

Cupriavidus taiwanensis forms proficient symbioses with a few Mimosa species. Inactivation of a type III protein secretion system (T3SS) had no effect on Mimosa pudica but allowed C. taiwanensis to establish chronic infections and fix nitrogen in Leucaena leucocephala. Unlike what was observed for other rhizobia, glutamate rather than plant flavonoids mediated transcriptional activation of this atypical T3SS.