Regulation of Glutamine and Glutamate Metabolism by GlnR and GlnA in Streptococcus pneumoniae

• Published in: The Journal of biological chemistry Vol. 281; no. 35; pp. 25097 - 25109
• Main Authors: Kloosterman, Tomas G., Hendriksen, Wouter T., Bijlsma, Jetta J.E., Bootsma, Hester J., van Hijum, Sacha A.F.T., Kok, Jan, Hermans, Peter W.M., Kuipers, Oscar P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2006; American Society for Biochemistry and Molecular Biology
• Subjects: Base Sequence; Cell Adhesion; DNA Primers - chemistry; Epithelial Cells; Glutamate-Ammonia Ligase - metabolism; Glutamic Acid - chemistry; Glutamine - chemistry; Humans; Molecular Sequence Data; Pentose Phosphate Pathway; Plasmids - metabolism; Quaternary Ammonium Compounds - metabolism; Repressor Proteins - metabolism; Streptococcus pneumoniae; Streptococcus pneumoniae - metabolism; Streptococcus pneumoniae - pathogenicity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M601661200

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.