Molecular characterization and symbiotic importance of prsD gene of Rhizobium leguminosarum bv. trifolii TA1

The prsD, prsE and orf3 genes of Rhizobium leguminosarum bv trifolii strain TA1 encode the proteins which are significantly related to the family of b acterial ABC transporters type I secretion systems. The prsD:Km(r) mutant o f strain TA1 induced non-nitrogen-fixing nodules on Trifolium pratense. Mic roscopic analysis of the nodules induced by prsD mutant did not reveal majo r abberations in the bacteroid appearance. The exopolysaccharide of prsD mu tant was produced in increased amount and its level of polymerization was c hanged. SDS/PAGE of the proteins from the culture supernatants showed a lac k of the 47-kDa protein in the. culture of prsD mutant. Thus, PrsD may play a role in the export of this protein.