Identification and characterization of uptake systems for glucose and fructose in Rhodococcus jostii RHA1.

Rhodococcusjostii RHA1 takes up and utilizes glucose and fructose as its sole carbon source. To address glucose and fructose transport systems in RHA1, an in silico analysis was performed. BLAST searches revealed that the ro02365 and ro06844 genes share 51 and 47% amino acid identity, respectively, with the major facilitator superfamily (MFS) glucose transporter, GlcP, of Streptomycescoelicolor A3(2) and the ro01549-01552 and ro06781-06785 loci share 43-51% amino acid identity with proteins of the phosphotransferase system (PTS) in S. coelicolor A3(2). Real-time reverse transcription-polymerase chain reaction analysis indicated that ro02365 and ro06781 were upregulated during growth on glucose and fructose, respectively. The ro06781 gene is an ortholog of the histidine-containing phosphocarrier protein in the PTS. Deletion mutants of ro02365 and ro06781 failed to grow on glucose and fructose, respectively, indicating that these genes are essential for growth on the corresponding sugar. They also failed to take up glucose and fructose, respectively. Hence ro02365 is responsible for the uptake of glucose as a MFS transporter and was designated as glcP, and ro06781 is responsible for the uptake of fructose as a component of the PTS and was designated as ptsH.