scholarly journals Elucidating the correlation between the number of TTTTGAT heptamer repeats and cholera toxin promoter activity in Vibrio cholerae O1 pandemic strains

2021 ◽  
Author(s):  
Arindam Naha ◽  
Jeffrey H Withey ◽  
Piyali Mukherjee ◽  
Rudra Narayan Saha ◽  
Prosenjit Samanta ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Transcriptional Activation ◽  
Promoter Activity ◽  
Watery Diarrhoea ◽  
Transcriptional Activators ◽  
Regulatory Cascade ◽  
Vibrio Cholerae O1 ◽  
Pandemic Strains ◽  
Heptad Repeats

A complex regulatory cascade controls expression of the cholera toxin genes (ctxAB) in Vibrio cholerae; which eventually leads to choleragen (CT) production and secretion, resulting in rice watery diarrhoea. The cholera toxin promoter (PctxAB) contains a series of heptad repeats (5′-TTTTGAT-3′); which have been previously shown to play crucial role in ctxAB transcriptional regulation by recruiting the transcriptional activators ToxT, ToxR, and the nucleoid-associated protein H-NS along the ctx promoter. The numbers of these repeats vary between the two biotypes of V. cholerae O1 strains, and even among strains of the same biotype. In this study, we examined PctxAB activation of V. cholerae O1 pandemic strains to understand the significance of the distal heptad repeats in regulating ctx expression. Interestingly, we found that ctx activation may depend on the number of TTTTGAT heptad repeats within PctxAB, and we posit that the occupation of the distal repeats by H-NS could further prevent transcriptional activation of ctx genes in V. cholerae. We hypothesize that ToxT-dependent transcriptional activation may not require entire displacement of H-NS and propose a revision in the currently accepted model of ToxT dependent PctxAB transcriptional activation.

The mouse homeodomain protein Phox2 regulates Ncam promoter activity in concert with Cux/CDP and is a putative determinant of neurotransmitter phenotype

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 881-896 ◽  
Author(s):  
I. Valarche ◽  
J.P. Tissier-Seta ◽  
M.R. Hirsch ◽  
S. Martinez ◽  
C. Goridis ◽  
...  
Keyword(s):  
Nervous System ◽  
Cell Adhesion ◽  
Peripheral Nervous System ◽  
Transcriptional Activation ◽  
Promoter Activity ◽  
Regulatory Element ◽  
Homeodomain Protein ◽  
Sensory Ganglia ◽  
Homeodomain Proteins ◽  
Regulatory Cascade

Transcriptional regulation of the gene encoding the cell adhesion receptor NCAM (neural cell adhesion molecule), a putative effector molecule of a variety of morphogenetic events, is likely to involve important regulators of morphogenesis. Here we identify two mouse homeodomain proteins that bind to an upstream regulatory element in the Ncam promoter: Cux, related to Drosophila cut and human CDP, and Phox2, a novel protein with a homeodomain related to that of the Drosophila paired gene. In transient transfection experiments, Cux was found to be a strong inhibitor of Ncam promoter activity, and this inhibition could be relieved by simultaneously overexpressing Phox2. These results suggest that the Ncam gene might be a direct target of homeodomain proteins and provide a striking example of regulatory cross-talk between homeodomain proteins of different classes. Whereas the expression pattern of Cux/CDP includes many NCAM-negative sites, Phox2 expression was restricted to cells also expressing Ncam or their progenitors. The localisation data thus strongly reinforce the notion that Phox2 plays a role in transcriptional activation of Ncam in Phox2-positive cell types. In the peripheral nervous system, Phox2 was strongly expressed in all ganglia of the autonomic nervous system and more weakly in some cranial sensory ganglia, but not in the sensory ganglia of the trunk. Phox2 transcripts were detected in the primordia of sympathetic ganglia as soon as they form. Phox2 expression in the brain was confined to spatially restricted domains in the hindbrain, which correspond to the noradrenergic and adrenergic nuclei once they are identifiable. All Phox2-expressing components of the peripheral nervous system are at least transiently adrenergic or noradrenergic. In the developing brain, Phox2 was expressed at all known locations of (nor)adrenergic neurones and of their precursors. These results suggest that Phox2, in addition to regulating the NCAM gene, may be part of the regulatory cascade that controls the differentiation of neurons towards this neurotransmitter phenotype.

scholarly journals Variation in Epitopes of the B Subunit of El Tor and Classical Biotype Vibrio cholerae O1 Cholera Toxin

Microbiology ◽  
1989 ◽  
Vol 135 (5) ◽  
pp. 1195-1200 ◽  
Author(s):  
M. L. Tamplin ◽  
M. K. Ahmed ◽  
R. Jalali ◽  
R. R. Colwell
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
B Subunit ◽  
Vibrio Cholerae O1 ◽  
El Tor

scholarly journals Vibrio cholerae H-NS Silences Virulence Gene Expression at Multiple Steps in the ToxR Regulatory Cascade

2000 ◽  
Vol 182 (15) ◽  
pp. 4295-4303 ◽  
Author(s):  
Melinda B. Nye ◽  
James D. Pfau ◽  
Karen Skorupski ◽  
Ronald K. Taylor
Keyword(s):  
Gene Expression ◽  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Transcriptional Start Site ◽  
Regulatory Protein ◽  
Virulence Gene ◽  
Virulence Gene Expression ◽  
Activator Proteins ◽  
Regulatory Cascade ◽  
Genes Encoding

ABSTRACT H-NS is an abundant nucleoid-associated protein involved in the maintenance of chromosomal architecture in bacteria. H-NS also has a role in silencing the expression of a variety of environmentally regulated genes during growth under nonpermissive conditions. In this study we demonstrate a role for H-NS in the negative modulation of expression of several genes within the ToxR virulence regulon ofVibrio cholerae. Deletion of hns resulted in high, nearly constitutive levels of expression of the genes encoding cholera toxin, toxin-coregulated pilus, and the ToxT virulence gene regulatory protein. For the cholera toxin- and ToxT-encoding genes, elevated expression in an hns mutant was found to occur in the absence of the cognate activator proteins, suggesting that H-NS functions directly at these promoters to decrease gene expression. Deletion analysis of the region upstream of toxT suggests that an extensive region located far upstream of the transcriptional start site is required for complete H-NS-mediated repression of gene expression. These data indicate that H-NS negatively influences multiple levels of gene expression within the V. choleraevirulence cascade and raise the possibility that the transcriptional activator proteins in the ToxR regulon function to counteract the repressive effects of H-NS at the various promoters as well as to recruit RNA polymerase.

scholarly journals Cholera Toxin Production by the El Tor Variant of Vibrio cholerae O1 Compared to Prototype El Tor and Classical Biotypes

2010 ◽  
Vol 48 (11) ◽  
pp. 4283-4286 ◽  
Author(s):  
J. Ghosh-Banerjee ◽  
M. Senoh ◽  
T. Takahashi ◽  
T. Hamabata ◽  
S. Barman ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Toxin Production ◽  
Vibrio Cholerae O1 ◽  
El Tor

scholarly journals Multilocus genetic analysis reveals that the Australian strains of Vibrio cholerae O1 are similar to the pre-seventh pandemic strains of the El Tor biotype

2009 ◽  
Vol 58 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Ashrafus Safa ◽  
Nurul A. Bhuiyan ◽  
Denise Murphy ◽  
John Bates ◽  
Suraia Nusrin ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Genetic Screening ◽  
Phenotypic Traits ◽  
Pfge Analysis ◽  
Genotype 2 ◽  
Environmental Reservoir ◽  
Vibrio Cholerae O1 ◽  
Pandemic Strains ◽  
Genomic Regions ◽  
El Tor

Episodes of cholera stemming from indigenous Vibrio cholerae strains in Australia are mainly associated with environmental sources. In the present study, 10 V. cholerae O1 strains of Australian origin were characterized. All of the strains were serogroup O1 and their conventional phenotypic traits categorized them as belonging to the El Tor biotype. Genetic screening of 12 genomic regions that are associated with virulence in V. cholerae showed variable results. Analysis of the ctxAB gene showed that the Australian environmental reservoir contains both toxigenic and non-toxigenic V. cholerae strains. DNA sequencing revealed that all of the toxigenic V. cholerae strains examined were of ctxB genotype 2. Whole genome PFGE analysis revealed that the environmental toxigenic V. cholerae O1 strains were more diverse than the non-toxigenic environmental O1 strains, and the absence of genes that make up the Vibrio seventh pandemic island-I and -II in all of the strains indicates their pre-seventh pandemic ancestry.

Classical RS1 and environmental RS1 elements in Vibrio cholerae O1 El Tor strains harbouring a tandem repeat of CTX prophage: revisiting Mozambique in 2005

2010 ◽  
Vol 59 (3) ◽  
pp. 302-308 ◽  
Author(s):  
Seon Young Choi ◽  
Je Hee Lee ◽  
Eun Jin Kim ◽  
Hye Ri Lee ◽  
Yoon-Seong Jeon ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Tandem Repeat ◽  
Small Chromosome ◽  
Classical Type ◽  
Large Chromosome ◽  
New Type ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor

Currently, Vibrio cholerae O1 serogroup biotype El Tor strains producing classical type cholera toxin (altered strains or El Tor variants) are prevalent in Asia and in Mozambique. Mozambican strains collected in 2004 contained a tandem repeat of CTX prophage on the small chromosome and each CTX prophage harboured the classical rstR and classical ctxB. We found that the majority of the strains collected in 2005 in Mozambique contained extra elements on the large chromosome in addition to the tandem repeat of CTX prophage on the small chromosome. New type RS1 elements RS1cla and RS1env, and a CTXenv with rstR env and the classical ctxB were identified on the large chromosome of the Mozambican isolates collected in 2005.

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