Inability to Catabolize Rhamnose by Rm1021 Affects Competition for Nodule Occupancy.

strains unable to grow on rhamnose as a sole carbon source are less competitive for nodule occupancy. To determine if the ability to use rhamnose as a sole carbon source affects competition for nodule occupancy in , Tn mutants unable to use rhamnose as a sole carbon source were isolated. mutations affecting rhamnose utilization were found in two operons syntenous to those of .

The Sugar Kinase That Is Necessary for the Catabolism of Rhamnose in Rhizobium leguminosarum Directly Interacts with the ABC Transporter Necessary for Rhamnose Transport.

Unlabelled: Rhamnose catabolism in Rhizobium leguminosarum was found to be necessary for the ability of the organism to compete for nodule occupancy. Characterization of the locus necessary for the catabolism of rhamnose showed that the transport of rhamnose was dependent upon a carbohydrate uptake transporter 2 (CUT2) ABC transporter encoded by rhaSTPQ and on the presence of RhaK, a protein known to have sugar kinase activity. A linker-scanning mutagenesis analysis of rhaK showed that the kinase and transport activities of RhaK could be separated genetically.