CrgA is an inducible LysR-type regulator of Neisseria meningitidis, acting both as a repressor and as an activator of gene transcription.
The crgA gene of Neisseria meningitidis, which codes for a LysR-type regulator, is divergently oriented with respect to the mdaB gene, which codes for a hypothetical NADPH-quinone oxidoreductase. Transcriptional studies of the intergenic region between crgA and mdaB showed that two overlapping and divergent promoters, P(crgA) and P(mdaB), control transcription of these genes. Deletion of the crgA gene led to a strong increase in transcription from the P(crgA) promoter and a concomitant strong decrease in transcription from the P(mdaB) promoter, indicating that CrgA acts both as an autorepressor of transcription at its own promoter and as an activator of transcription at the mdaB promoter. Addition of alpha-methylene-gamma-butyrolactone (MBL), an inducer of NADPH-quinone oxidoreductase, to wild-type N. meningitidis cells specifically resulted in further activation of transcription of the P(mdaB) promoter and more repression of transcription of the P(crgA) promoter. No such regulation was observed when MBL was added to crgA-deficient cells, indicating that the transcriptional response to MBL is CrgA mediated. Under the same experimental conditions, no regulation of transcription by either CrgA or MBL was detected at the pilus and capsule genes. The role of CrgA in the regulation of gene expression during the infectious cycle of N. meningitidis is discussed.
Ieva
Raffaele
R
Biochemistry and Molecular Biology Unit, Chiron Vaccines, 53100 Siena, Italy.
Alaimo
Cristina
C
Delany
Isabel
I
Spohn
Gunther
G
Rappuoli
Rino
R
Scarlato
Vincenzo
V
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D016667:Bacterial Capsules / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D010861:Fimbriae, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics; D009345:Neisseria meningitidis / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*
D001426:Bacterial Proteins; C406769:CrgA protein, Neisseria meningitidis; D014157:Transcription Factors; C014096:alpha-methylene gamma-butyrolactone; C073470:LysR protein, Bacteria; D016660:NAD(P)H Dehydrogenase (Quinone); D015107:4-Butyrolactone