Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official. Federal government websites often end in VSports app下载. gov or . mil. Before sharing sensitive information, make sure you’re on a federal government site. .

Https

The site is secure V体育官网. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. .

. 2005 Mar 8;102(10):3800-4.
doi: 10.1073/pnas.0406805102. Epub 2005 Feb 22.

VSports手机版 - Microsatellite instability regulates transcription factor binding and gene expression

Patricia Martin  1 , Katherine Makepeace, Stuart A Hill, Derek W Hood, E Richard Moxon
Affiliations

Microsatellite instability regulates transcription factor binding and gene expression (VSports最新版本)

Patricia Martin et al. Proc Natl Acad Sci U S A. .

Abstract

Microsatellites are tandemly repeated simple sequence DNA motifs widely prevalent in eukaryotic and prokaryotic genomes. In pathogenic bacteria, instability of these hypermutable loci through slipped-strand mispairing mediates the high-frequency reversible switching of phenotype expression, i. e VSports手机版. , phase variation. Phase-variable expression of NadA, an outer membrane protein and adhesin of the pathogen Neisseria meningitidis, is mediated by changes in the number of TAAA repeats located upstream of the core promoter of nadA. Here we report that loss or gain of TAAA repeats affects the binding of the transcriptional regulatory protein IHF to the nadA promoter. Thus, phase-variable transcription of nadA potentially incorporates interplay between stochastic (mutational) and prescriptive (classical) mechanisms of gene regulation. .

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.
Level of transcription of the nadA gene related to the number of repeated TAAA motifs. (A and B) Transcription in variants of N. meningitidis strain MC58 (A) and in strains of N. meningitidis (B). The bars represent the means and SEs of at least four independent measurements by RT-PCR, performed and analyzed as described (12). AU, arbitrary units. The program imagequant was used to calculate the amount of nadA cDNA normalized with the amount the housekeeping gene gdh cDNA. Pairwise comparisons of the data sets from each variant or strain were performed by using graphpad software. With P < 0.05 as a cut-off, three distinct classes emerged. The gray bars represent high, the white bars low, and the black bars intermediate levels of nadA transcription. (C) Recapitulation of the level of nadA transcription related to the number of repeated TAAA motifs. *, No variant or strain with seven repeats was available for analysis. The repeating pattern of transcription is indicated.
Fig. 2.
Fig. 2.
Identification of putative binding sites for Fur and IHF proteins in the DNA sequence located from nucleotide -159 to nucleotide +30, with respect to the nadA transcription initiation site. The repeat tract is indicated in bold. Neisseria Fur (17) and IHF (28) core binding site consensus sequences are indicated above and below the DNA sequence, respectively. The matching bases are underlined. N, A, T, C, or G; W, A, or T.
Fig. 3.
Fig. 3.
EMSA of the nadA promoter. (A) Schematic representation of the DNA region flanking the repeat tract. The transcription initiation nucleotide is indicated by an arrow and labeled +1. The -10 and -35 elements are indicated with black boxes. The coordinates of the repeat tract and of the upstream gene are indicated. The DNA fragments used as probes are indicated as hatched horizontal bars. (B) EMSA analysis of the promoter-proximal regions of the nadA gene. The probes and the amount of proteins used are specified. *, Retarded bands in analyses 1–5 and an excess of unlabeled probe was added to the reaction in analysis 6.
Fig. 4.
Fig. 4.
Deletions of the DNA sequences located upstream from the nadA core promoter and level of nadA transcription associated with the deletions. (A) WT: schematic representation of the DNA region flanking the repeat tract. The symbols used are the same as in Fig. 3. (B–F) Deletions are indicated by the dashed lines. The mutant names are indicated to the left. The level of nadA transcription was measured by RT-PCR in two independent experiments and is shown to the right. The lanes TAAA10 and TAAA9 show the pattern of expression observed when the intact nadA gene is expressed at a high and a low level, respectively. Lanes 1 and 2 show the patterns of expression obtained for two independent mutants having the same deletion. The upper band shows the level of nadA transcription, and the lower band the level of housekeeping gdh gene transcription.
Fig. 5.
Fig. 5.
Level of nadA transcription in mutants Δ221–108 and Δ984–108. The deletions are represented as in Fig. 4. The vertical arrow indicates that the deleted (TAAA)8 variants were obtained after passage of the deleted (TAAA)9 mutants.
See this image and copyright information in PMC

References (VSports在线直播)

    1. Johnson, C. R., Newcombe, J., Thorne, S., Borde, H. A., Eales-Reynolds, L. J., Gorringe, A. R., Funnell, S. G. & McFadden, J. J. (2001) Mol. Microbiol. 39, 1345-1355. - PubMed
    1. Deghmane, A. E., Giorgini, D., Larribe, M., Alonso, J. M. & Taha, M. K. (2002) Mol. Microbiol. 43, 1555-1564. - V体育官网 - PubMed
    1. Morelle, S., Carbonnelle, E. & Nassif, X. (2003) J. Bacteriol. 185, 2618-2627. - PMC - PubMed
    1. Moxon, E. R., Rainey, P. B., Nowak, M. A. & Lenski, R. E. (1994) Curr. Biol. 4, 24-33. - PubMed (VSports手机版)
    1. Hammerschmidt, S., Hilse, R., van Putten, J. P., Gerardy-Schahn, R., Unkmeir, A. & Frosch, M. (1996) EMBO J. 15, 192-198. - PMC - PubMed

Publication types

MeSH terms

Substances