Regulation of glutamine and glutamate metabolism by GlnR and GlnA in Streptococcus pneumoniae.
Several genes involved in nitrogen metabolism are known to contribute to the virulence of pathogenic bacteria. Here, we studied the function of the nitrogen regulatory protein GlnR in the Gram-positive human pathogen Streptococcus pneumoniae. We demonstrate that GlnR mediates transcriptional repression of genes involved in glutamine synthesis and uptake (glnA and glnPQ), glutamate synthesis (gdhA), and the gene encoding the pentose phosphate pathway enzyme Zwf, which forms an operon with glnPQ. Moreover, the expression of gdhA is also repressed by the pleiotropic regulator CodY. The GlnR-dependent regulation occurs through a conserved operator sequence and is responsive to the concentration of glutamate, glutamine, and ammonium in the growth medium. By means of in vitro binding studies and transcriptional analyses, we show that the regulatory function of GlnR is dependent on GlnA. Mutants of glnA and glnP displayed significantly reduced adhesion to Detroit 562 human pharyngeal epithelial cells, suggesting a role for these genes in the colonization of the host by S. pneumoniae. Thus, our results provide a thorough insight into the regulation of glutamine and glutamate metabolism of S. pneumoniae mediated by both GlnR and GlnA.
Kloosterman
Tomas G
TG
Department of Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, PO Box 14, 9750 AA Haren, The Netherlands.
Hendriksen
Wouter T
WT
Bijlsma
Jetta J E
JJ
Bootsma
Hester J
HJ
van Hijum
Sacha A F T
SA
Kok
Jan
J
Hermans
Peter W M
PW
Kuipers
Oscar P
OP
D001483:Base Sequence; D002448:Cell Adhesion; D017931:DNA Primers / Q000737:chemistry; D004847:Epithelial Cells; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D018698:Glutamic Acid / Q000737:chemistry*; D005973:Glutamine / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D010427:Pentose Phosphate Pathway; D010957:Plasmids / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000378:metabolism* / Q000472:pathogenicity
D017931:DNA Primers; D000644:Quaternary Ammonium Compounds; D012097:Repressor Proteins; D005973:Glutamine; D018698:Glutamic Acid; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase