Down-regulation of pili and capsule of Neisseria meningitidis upon contact with epithelial cells is mediated by CrgA regulatory protein.
The initial attachment of Neisseria meningitidis to the target cell surface appears to be largely pilus depend-ent in capsulated bacteria. Intimate adhesion subsequently occurs to permit colonization. We recently reported that insertional inactivation of the crgA gene, which encodes a transcriptional regulator belonging to the LysR family, decreased meningococcal adhesion to epithelial cells and abolished intimate adhesion. In this report, we analyse expression of the pilE and sia genes, which are involved in the biosynthesis of pili and capsule respectively, during bacteria-host cell interactions. Western blotting, transcriptional fusion and reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that the expression of these genes was downregulated during intimate adhesion. DNA-binding assays, footprinting and RT-PCR analysis indicated that this downregulation was directly mediated by the CrgA protein. The pilE and sia promoters were found to have a CrgA binding motif in common. These results strongly suggest that N. meningitidis displays an adaptive response upon cell contact. CrgA may play a central regulatory role in meningococcal adhesion, particularly in switching from initial to intimate adhesion by downregulating the bacterial surface structures that hinder this adhesion.
Deghmane
Ala-Eddine
AE
Unité des Neisseria, 28 rue du Docteur Roux, 75724, Paris, Cedex 15, France.
Giorgini
Dario
D
Larribe
Mireille
M
Alonso
Jean-Michel
JM
Taha
Muhamed-Kheir
MK
D001422:Bacterial Adhesion; D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation; D004847:Epithelial Cells / Q000382:microbiology; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009345:Neisseria meningitidis / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D001426:Bacterial Proteins; C406769:CrgA protein, Neisseria meningitidis; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D014157:Transcription Factors; C074063:pilE protein, Neisseria gonorrhoeae; D036781:Fimbriae Proteins