Inactivation of the Streptococcus mutans fxpC Gene Confers Resistance to Xylitol, a Caries-preventive Natural Carbohydrate Sweetener

2002 ◽  
Vol 81 (6) ◽  
pp. 380-386 ◽  
Author(s):  
H. Benchabane ◽  
L.-A. Lortie ◽  
N.D. Buckley ◽  
L. Trahan ◽  
M. Frenette
Keyword(s):  
Streptococcus Mutans ◽  
Northern Blot Analysis ◽  
Regulatory Protein ◽  
Open Reading Frames ◽  
Phosphotransferase System ◽  
Chain Reactions ◽  
Polymerase Chain Reactions ◽  
Resistant Strains ◽  
Polymerase Chain ◽  
Reading Frames

Xylitol is transported by Streptococcus mutans via a constitutive phosphoenolpyruvate:fructose phosphotransferase system (PTS) composed of a IIABC protein. Spontaneous xylitol-resistant strains are depleted in constitutive fructose-PTS activity, exhibit additional phenotypes, and are associated with the caries-preventive properties of xylitol. Polymerase chain-reactions and chromosome walking were used to clone the fxp operon that codes for the constitutive fructose/xylitol-PTS. The operon contained three open reading frames: fxpA, which coded for a putative regulatory protein of the deoxyribose repressor (DeoR) family, fxpB, which coded for a 1-phosphofructokinase, and fxpC, which coded for a IIABC protein of the fructose-PTS family. Northern blot analysis revealed that these genes were co-transcribed into a 4.4-kb mRNA even in the absence of fructose. Inactivation of the fxpC gene conferred resistance to xylitol, confirming its function. The fxp operon is also present in the genomes of other xylitol-sensitive streptococci, which could explain their sensitivity to xylitol.

Gene cloning and difference analysis of vitellogenin in Neoseiulus barkeri (Hughes)

2017 ◽  
Vol 108 (2) ◽  
pp. 141-149 ◽  
Author(s):  
L. Ding ◽  
F. Chen ◽  
R. Luo ◽  
Q. Pan ◽  
C. Wang ◽  
...  
Keyword(s):  
Resistant Strain ◽  
Open Reading Frames ◽  
Neoseiulus Barkeri ◽  
Type D ◽  
Resistant Strains ◽  
Polymerase Chain ◽  
Factor Type ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Reading Frames

AbstractNeoseiulus barkeri (HUGHES) is the natural enemy of spider mites, whiteflies and thrips. Screening for chemically-resistant predatory mites is a practical way to balance the contradiction between the pesticide using and biological control. In this study, the number of eggs laid by fenpropathrin-susceptible and resistant strains of N. barkeri was compared. Additionally, we cloned three N. barkeri vitellogenin (Vg) genes and used quantitative real-time polymerase chain reaction to quantify Vg expression in susceptible and resistant strains. The total number of eggs significantly increased in the fenpropathrin-resistant strain. The full-length cDNA cloning of three N. barkeri Vg genes (NbVg1, NbVg2 and NbVg3) revealed that the open reading frames of NbVg1, NbVg2 and NbVg3 were 5571, 5532 and 4728 bp, encoding 1856, 1843 and 1575 amino acids, respectively. The three N. barkeri Vg possessed the Vitellogenin-N domain (or lipoprotein N-terminal domain (LPD_N)), von Willebrand factor type D domain (VWD) and the domain with unknown function 1943 (DUF1943). The NbVg1 and NbVg2 expression levels were significantly higher in the resistant strain than in the susceptible strain, while the NbVg3 expression level was lower in the resistant strain. Thus, we speculate that the increased number of eggs laid by the fenpropathrin-resistant strain of N. barkeri may be a consequence of changes in Vg gene expression.

scholarly journals Regulated Expression of the Streptococcus mutans dltGenes Correlates with Intracellular Polysaccharide Accumulation

1999 ◽  
Vol 181 (8) ◽  
pp. 2363-2372 ◽  
Author(s):  
Grace A. Spatafora ◽  
Megan Sheets ◽  
Rebecca June ◽  
David Luyimbazi ◽  
Katherine Howard ◽  
...  
Keyword(s):  
Amino Acid ◽  
Streptococcus Mutans ◽  
Growth Phase ◽  
Lactobacillus Rhamnosus ◽  
Constitutive Expression ◽  
Sole Source ◽  
Amino Acid Sequences ◽  
Open Reading Frames ◽  
Phosphotransferase System ◽  
Reading Frames

ABSTRACT Intracellular polysaccharides (IPS) are glycogen-like storage polymers which contribute significantly to Streptococcus mutans-induced cariogenesis. We previously identified and cloned a locus from the S. mutans chromosome which is required for the accumulation of IPS. Sequencing of this locus revealed at least four contiguous open reading frames, all of which are preceded by a common promoter region and are transcribed in the same direction. Analysis of the amino acid sequence deduced from the first of these open reading frames (ORF1) revealed domains which are highly conserved among d-alanine-activating enzymes (DltA) inLactobacillus rhamnosus (formerlyLactobacillus casei) and Bacillus subtilis. The deduced amino acid sequences derived from ORF2, -3, and -4 also exhibit extensive similarity to DltB, -C, and -D, respectively, in these microorganisms. However, Southern hybridization experiments indicate that this operon maps to a locus on the S. mutanschromosome which is separate from the glgP,glgA, and glgD genes, whose products are known mediators of bacterial IPS accumulation. We therefore assigned a newdlt designation to the locus which we had formerly calledglg. We maintain that the dlt genes are involved in S. mutans IPS accumulation, however, since they complement a mutation in trans which otherwise rendersS. mutans IPS deficient. In this study, we found that expression of the S. mutans dlt genes is growth phase dependent and is modulated by carbohydrates internalized via the phosphoenolpyruvate phosphotransferase system (PTS). We demonstrated that the S. mutans dlt genes are expressed constitutively when non-PTS sugars are provided as the sole source of carbohydrate. Consistent with a role for the PTS in dltexpression is a similar constitutive expression of the dltgenes in an S. mutans PTS mutant grown in a chemically defined medium supplemented with glucose. In summary, these findings support a novel role for the dlt gene products inS. mutans IPS accumulation and suggest thatdlt expression in this oral pathogen is subject to complex mechanisms of control imposed by growth phase, dietary carbohydrate, and other factors present in the plaque environment.

scholarly journals Investigation of Lethal Concurrent Outbreak of Chlamydiosis and Pigeon Circovirus in a Zoo

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1654
Author(s):  
Wei-Tao Chen ◽  
Chin-Ann Teng ◽  
Cheng-Hsin Shih ◽  
Wei-Hsiang Huang ◽  
Yi-Fan Jiang ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Chlamydia Psittaci ◽  
Bursa Of Fabricius ◽  
Chain Reactions ◽  
Renal Epithelium ◽  
Polymerase Chain Reactions ◽  
Transmission Electron ◽  
Intracytoplasmic Inclusion Bodies ◽  
Polymerase Chain ◽  
Streptopelia Orientalis

During the spring, an outbreak of sudden death involving 58 birds occurred in a zoo. Histopathological examinations revealed variable numbers of intracytoplasmic basophilic microorganisms in the macrophages, hepatocytes, and renal epithelium of most birds, along with occasional botryoid intracytoplasmic inclusion bodies within histiocytes in the bursa of Fabricius. Based on the results of histopathological examinations, immunohistochemical staining, transmission electron microscopy, and polymerase chain reactions, genotype B Chlamydia psittaci infection concurrent with pigeon circovirus (PiCV) was diagnosed. A retrospective survey, including two years before the outbreak and the outbreak year, of C. psittaci and PiCV infections of dead birds in the aviaries, revealed that the outbreak was an independent episode. The findings of this study indicate that concurrent infection with C. psittaci and PiCV might lead to lethal outbreaks of chlamydiosis, particularly Streptopelia orientalis. In addition, persistently monitoring both pathogens and identifying potential PiCV carriers or transmitters might also help prevent lethal disease outbreaks.

scholarly journals Bias between the Left and Right Inverted Repeats during IS911 Targeted Insertion

2008 ◽  
Vol 190 (18) ◽  
pp. 6111-6118 ◽  
Author(s):  
P. Rousseau ◽  
C. Loot ◽  
C. Turlan ◽  
S. Nolivos ◽  
M. Chandler
Keyword(s):  
Insertion Sequence ◽  
Regulatory Protein ◽  
Open Reading Frames ◽  
Inverted Repeats ◽  
Functional Differences ◽  
Left And Right ◽  
Ordered Assembly ◽  
Overlapping Open Reading Frames ◽  
Reading Frames

ABSTRACT IS911 is a bacterial insertion sequence composed of two consecutive overlapping open reading frames (ORFs [orfA and orfB]) encoding the transposase (OrfAB) as well as a regulatory protein (OrfA). These ORFs are bordered by terminal left and right inverted repeats (IRL and IRR, respectively) with several differences in nucleotide sequence. IS911 transposition is asymmetric: each end is cleaved on one strand to generate a free 3′-OH, which is then used as the nucleophile in attacking the opposite insertion sequence (IS) end to generate a free IS circle. This will be inserted into a new target site. We show here that the ends exhibit functional differences which, in vivo, may favor the use of one compared to the other during transposition. Electromobility shift assays showed that a truncated form of the transposase [OrfAB(1-149)] exhibits higher affinity for IRR than for IRL. While there was no detectable difference in IR activities during the early steps of transposition, IRR was more efficient during the final insertion steps. We show here that the differential activities between the two IRs correlate with the different affinities of OrfAB(1-149) for the IRs during assembly of the nucleoprotein complexes leading to transposition. We conclude that the two inverted repeats are not equivalent during IS911 transposition and that this asymmetry may intervene to determine the ordered assembly of the different protein-DNA complexes involved in the reaction.

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