RT Journal
A1 Rosenow, Carsten
A1 Maniar, Mita
A1 Trias, Joaquim
T1 Regulation of the α-Galactosidase Activity in Streptococcus pneumoniae: Characterization of the Raffinose Utilization System
JF Genome Research 
JO Genome Research 
YR 1999 
FD December 01 
VO 9 
IS 12 
SP 1189 
OP 1197 
DO 10.1101/gr.9.12.1189 
UL http://genome.cshlp.org/content/9/12/1189.abstract 
AB A 10.2-kb gene region was identified in the Streptococcus pneumoniae genome sequence that contains eight genes involved in regulation and metabolism of raffinose. The genes rafR andrafS are transcribed as one operon, and their gene products regulate the raffinose-dependent stimulation of a divergently transcribed second promoter (PA
) directing the expression of aga, the structural gene for α-galactosidase. Raffinose-mediated transcription from PA
 results in a 500-fold increase in α-galactosidase activity in the cell. A third promoter within the cluster is responsible for the transcription of the remaining five genes (rafE, rafF, rafG,gtfA, and rafX), whose gene products might be involved in transport and metabolism of raffinose. The presence of additional internal promoters cannot be excluded. The agapromoter PA
 is negatively regulated by the presence of sucrose in the growth medium. Consistent with catabolite repression (CR), a DNA sequence with high homology to the CRE (cis-active element) was identified upstream of the aga promoter. Sucrose-mediated CR depends on the phosphoenolpyruvate: sucrose phosphotransferase system (PTS) but is unaffected by a mutation in a gene encoding a homolog of the CRE regulatory protein CcpA.