Mapping the Sinorhizobium meliloti 1021 solute-binding protein-dependent transportome

• DOI: 10.1073/pnas.0606673103
• Publication Date: 2006-11-14T01:38:56Z
• Authors: T. H. Mauchline; J. E. Fowler; A. K. East; A. L. Sartor; R. Zaheer; A. H. F. Hosie; P. S. Poole; T. M. Finan
• Keywords: 570; 0303 health sciences; Gene Expression Profiling; Molecular Sequence Data; Carbohydrates; Biological Transport; tripartite ATP-independent periplasmic; Gene Expression Regulation, Bacterial; 03 medical and health sciences; Pyrimidines; Bacterial Proteins; Genes, Reporter; Purines; expression; Operon; ATP-Binding Cassette Transporters; Amines; Amino Acids; Promoter Regions, Genetic; Acids; ATP-binding cassette; Plasmids; Sinorhizobium meliloti

The number of solute-binding protein-dependent transporters in rhizobia is dramatically increased compared with the majority of other bacteria so far sequenced. This increase may be due to the high affinity of solute-binding proteins for solutes, permitting the acquisition of a broad range of growth-limiting nutrients from soil and the rhizosphere. The transcriptional induction of these transporters was studied by creating a suite of plasmid and integrated fusions to nearly all ATP-binding cassette (ABC) and tripartite ATP-independent periplasmic (TRAP) transporters of Sinorhizobium meliloti . In total, specific inducers were identified for 76 transport systems, amounting to ≈47% of the ABC uptake systems and 53% of the TRAP transporters in S. meliloti . Of these transport systems, 64 are previously uncharacterized in Rhizobia and 24 were induced by solutes not known to be transported by ABC- or TRAP-uptake systems in any organism. This study provides a global expression map of one of the largest transporter families (transportome) and an invaluable tool to both understand their solute specificity and the relationships between members of large paralogous families.