Ribose utilization by the human commensal Bifidobacterium breve UCC2003.
Bottom Line: Growth of Bifidobacterium breve UCC2003 on ribose leads to the transcriptional induction of the rbsACBDK gene cluster.Generation and phenotypic analysis of an rbsA insertion mutant established that the rbs gene cluster is essential for ribose utilization, and that its transcription is likely regulated by a LacI-type regulator encoded by rbsR, located immediately upstream of rbsA.The rbsK gene of the rbs operon of B. breve UCC2003 was shown to specify a ribokinase (EC 18.104.22.168), which specifically directs its phosphorylating activity towards D-ribose, converting this pentose sugar to ribose-5-phosphate.
Affiliation: Alimentary Pharmabiotic Centre, Department of Microbiology, University College Cork, Western Road, Cork, Ireland.Show MeSH
Mentions: In B. breve UCC2003, the rbsA, rbsC, rbsB, rbsD and rbsK genes (Fig. 3B) are presumed to be expressed as a single transcript, based on their similar expression patterns as determined from microarray analysis and RT‐PCR experiments, which showed that amplification products were generated from cDNA (generated from total RNA of ribose‐grown B. breve UCC2003) using various primer combinations that spanned the individual genes of the rbs gene cluster (data not shown). Furthermore, the only predicted Rho‐independent terminator structure in the DNA region that harbours the very closely organized rbsACBDK genes is present downstream of the rbsK gene (Fig. 3B). The transcriptional start site of the presumed rbsABCDK operon was determined by primer extension analysis (see Experimental procedures in Supporting information) and it was shown to be located 125 bp upstream of the predicted rbsA start codon (Fig. 3A, I and II) and 7 bp downstream of sequences resembling consensus −10 and −35 sequences of a vegetative promoter.
Affiliation: Alimentary Pharmabiotic Centre, Department of Microbiology, University College Cork, Western Road, Cork, Ireland.