Biochemical and phenotypic characterisation of the transporter UspABC.

() is an intracellular human pathogen that has evolved to survive in a nutrient limited environment within the host for decades. Accordingly, has developed strategies to acquire scarce nutrients and the mycobacterial transporter systems provide an important route for the import of key energy sources. However, the physiological role of the transporters and their substrate preference(s) are poorly characterised. Previous studies have established that the UspC solute-binding domain recognises amino- and phosphorylated-sugars, indicating that the mycobacterial UspABC transporter plays a key role in the import of peptidoglycan precursors. Herein, we have used a wide array of approaches to investigate the role of UspABC in by analysis of mutant strains that either lack the solute binding domain: Δ or the entire transport complex: Δ. Analysis of mycobacterial transcripts shows that the system is functionally expressed in mycobacteria as a contiguous reading frame. Topology mapping confirms an N-C orientation of the UspAB integral membrane spanning domains. Phenotypic microarray profiling of commercially available sugars suggests, unexpectedly, that the and Δ mutants had different carbon utilisation profiles and that neither strain utilised glucose-1-phosphate. Furthermore, proteomics analysis showed an alteration in the abundance of proteins involved in sugar and lipid metabolism, crucial for cell envelope synthesis, and we propose that UspABC has an important role in determining the interplay between these pathways.