Regulation and differential expression of gdhA encoding NADP-specific glutamate dehydrogenase in Neisseria meningitidis clinical isolates.
Meningococcal gdhA, encoding the NADP-specific l-glutamate dehydrogenase (NADP-GDH), is essential for systemic infection in an infant rat model. In this paper, a limited transcriptional analysis detected differences in gdhA expression among clinical isolates. In strains expressing high levels of gdhA mRNA, two promoters, gdhA P1 and gdhA P2, initiated transcription of gdhA. In contrast, in strains expressing low mRNA levels, gdhA P2 was not active because of weak expression of gdhR, an associated regulatory gene. Gene knock-out and complementation of a gdhR-defective mutant confirmed that GdhR is a positive regulator for gdhA P2. Trans-activation of gdhA P2 was maximal in complex medium during late logarithmic growth phase and in chemical defined medium (MCDA) when glucose (MCDA-glucose) instead of lactate (MCDA-lactate) was used as a carbon source in the presence of glutamate. gdhR knock-out mutants lost both growth phase and carbon source regulation, and exhibited a growth defect more severe in MCDA-glucose than in MCDA-lactate. DNA-protein interaction studies demonstrated that 2-oxoglutarate, a product of the catabolic reaction of the NADP-GDH and an intermediate of the tricarboxylic acid (TCA) cycle, inhibits binding of GdhR to gdhA P2.
Dipartimento di Biologia e Patologia Cellulare e Molecolare L Califano, Università degli Studi di Napoli Federico II, Naples, Italy.
Caterina
C
Pagliarulo
Paola
P
Salvatore
Lucia Rosaria
LR
De Vitis
Roberta
R
Colicchio
Caterina
C
Monaco
Maurizio
M
Tredici
Adelfia
A
Talà
Marcellino
M
Bardaro
Alfredo
A
Lavitola
Carmelo B
CB
Bruni
Pietro
P
Alifano
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D018086:Glutamate Dehydrogenase (NADP+) / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000201:enzymology / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic
D017931:DNA Primers; D012329:RNA, Bacterial; D012333:RNA, Messenger; D018086:Glutamate Dehydrogenase (NADP+)