Analysis of transcriptional control mechanisms of capsule expression in Neisseria meningitidis

• Published in: International journal of medical microbiology 2001-11, Vol.291 (5), p.361-369
• Main Authors: von Loewenich, Friederike D., Wintermeyer, Eva, Dümig, Michaela, Frosch, Matthias
• Format: Article
• Language: English
• Subjects: Animal viral diseases; Bacterial Capsules - biosynthesis; Bacterial Capsules - genetics; Bacterial diseases; Bacterial diseases of the genital system; Bacterial Proteins - genetics; Base Sequence; beta-Galactosidase - genetics; beta-Galactosidase - metabolism; Biological and medical sciences; capsule expression; DNA-Binding Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Human bacterial diseases; Infectious diseases; Lac Operon - genetics; lacZ reporter gene fusion; Medical sciences; Microbiology; Molecular Sequence Data; Mutation; Neisseria meningitidis; Neisseria meningitidis - classification; Neisseria meningitidis - genetics; Neisseria meningitidis - pathogenicity; Promoter Regions, Genetic - genetics; Racemases and Epimerases; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Homology, Nucleic Acid; siaA gene; Transcription Factors - genetics; Transcription, Genetic; transcriptional control; Viral diseases; Virulence; virulence factors
• ISSN: 1438-4221; 1618-0607
• DOI: 10.1078/1438-4221-00142

The major virulence factor which contributes to the survival of Neisseria meningitidis in the blood stream and the cerebrospinal fluid is the capsular polysaccharide. Expression of the capsule genes of N. meningitidis serogroups B, C, W-135 and Y is controlled by an intergenic region separating the capsule biosynthesis operon ( siaA-D) and the capsule transport operon ( ctrA-D). To further investigate capsule expression in N. meningitidis we amplified and sequenced the intergenic region of 42 meningococcal isolates of different serogroups. Sequence variations were found mainly in a repeat region preceding the siaA start codon. Correlation between sequence variation and serogroup could not be observed. To measure the transcriptional and translational activity of the respective intergenic regions we performed transcriptional and translational fusions with the lacZ gene integrated into the chromosome of N. meningitidis. Sequence variations preceding the siaA start codon had no effect on β-galactosidase activity. Different in vitro growth conditions such as temperature, glucose concentration, osmolarity, pH and iron concentration also did not influence β-galactosidase activity. Sequential deletions of the intergenic region showed that an Up-like element adjacent to the predicted -35 box is necessary for full transcriptional activity. The deletion of the untranslated region preceding the siaA start codon led to a threefold higher β-galactosidase activity compared with the full-length construct suggesting that the respective region may be involved in capsule regulation.