scholarly journals Interaction of the Gifsy-1 Xis Protein with the Gifsy-1 attP Sequence

2007 ◽  
Vol 189 (17) ◽  
pp. 6303-6311 ◽  
Author(s):  
Asa Flanigan ◽  
Jeffrey F. Gardner
Keyword(s):  
Dimethyl Sulfate ◽  
Direct Repeats ◽  
Mobility Shift ◽  
Base Pairs ◽  
Recombination Mechanism ◽  
Site Specific ◽  
Dnase I Footprinting ◽  
Pair Sequence ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT The Gifsy-1 phage integrates site specifically into the Salmonella chromosome via an integrase-mediated site-specific recombination mechanism. Initial genetic analysis suggests that Gifsy-1 integrase-mediated excision of the Gifsy-1 phage is influenced by proteins encoded by both the Gifsy-1 and the Gifsy-2 phages. Our studies show that the Gifsy-1 Xis protein regulates the directionality of integrase-mediated excision of the Gifsy-1 phage. Electrophoretic mobility shift assays, DNase I footprinting, dimethyl sulfate (DMS) interference assays, and DMS protection assays were used to identify a 31-base-pair sequence in the attP region to which the Gifsy-1 protein binds. The results suggest that this recombination directionality factor binds in vitro to three imperfect direct repeats, spaced 10 base pairs apart, in a sequential and cooperative manner in the absence of other phage-encoded proteins. Our studies suggest that, while the Gifsy-1 Xis does not require additional factors for specific and high-affinity binding, it may form a microfilament on DNA similar to that described for the phage lambda Xis protein.

scholarly journals The ArgP Protein Stimulates the Klebsiella pneumoniae gdhA Promoter in a Lysine-Sensitive Manner

2008 ◽  
Vol 190 (12) ◽  
pp. 4351-4359 ◽  
Author(s):  
Thomas J. Goss
Keyword(s):  
Klebsiella Pneumoniae ◽  
Upstream Region ◽  
Mobility Shift ◽  
Base Pairs ◽  
Dnase I Footprinting ◽  
Sensitive Factor ◽  
Electrophoretic Mobility Shift Assays ◽  
Knockout Mutation

ABSTRACT The lysine-sensitive factor that binds to the upstream region of the Klebsiella pneumoniae gdhA promoter and stimulates gdhA transcription during growth in minimal medium has been proposed to be the K. pneumoniae ArgP protein (M. R. Nandineni, R. S. Laishram, and J. Gowrishankar, J. Bacteriol. 186:6391-6399, 2004). A knockout mutation of the K. pneumoniae argP gene was generated and used to assess the roles of exogenous lysine and argP in the regulation of the gdhA promoter. Disruption of argP reduced the strength and the lysine-dependent regulation of the gdhA promoter. Electrophoretic mobility shift assays using crude extracts prepared from wild-type and argP-defective strains indicted the presence of an argP-dependent factor whose ability to bind the gdhA promoter was lysine sensitive. DNase I footprinting studies using purified K. pneumoniae ArgP protein indicated that ArgP bound the region that lies approximately 50 to 100 base pairs upstream of the gdhA transcription start site in a manner that was sensitive to the presence of lysine. Substitutions within the region bound by ArgP affected the binding of ArgP to the gdhA promoter region in vitro and the argP-dependent stimulation of the gdhA promoter in vivo. These observations suggest that elevated intracellular levels of lysine reduce the affinity of ArgP for its binding site at the gdhA promoter, preventing ArgP from binding to and stimulating transcription from the promoter in vivo.

scholarly journals SlyA and H-NS Regulate Transcription of the Escherichia coli K5 Capsule Gene Cluster, and Expression of slyA in Escherichia coli Is Temperature-dependent, Positively Autoregulated, and Independent of H-NS

2007 ◽  
Vol 282 (46) ◽  
pp. 33326-33335 ◽  
Author(s):  
David Corbett ◽  
Hayley J. Bennett ◽  
Hamdia Askar ◽  
Jeffrey Green ◽  
Ian S. Roberts
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Regulation Of Transcription ◽  
Temperature Dependent ◽  
Mobility Shift ◽  
E Coli ◽  
Dnase I Footprinting ◽  
Nucleoprotein Complex ◽  
Electrophoretic Mobility Shift Assays

In this paper, we present the first evidence of a role for the transcriptional regulator SlyA in the regulation of transcription of the Escherichia coli K5 capsule gene cluster and demonstrate, using a combination of reporter gene fusions, DNase I footprinting, and electrophoretic mobility shift assays, the dependence of transcription on the functional interplay between H-NS and SlyA. Both SlyA and H-NS bind to multiple overlapping sites within the promoter in vitro, but their binding is not mutually exclusive, resulting in a remodeled nucleoprotein complex. In addition, we show that expression of the E. coli slyA gene is temperature-regulated, positively autoregulated, and independent of H-NS.

scholarly journals Characterization of the Organic Hydroperoxide Resistance System of Brucella abortus 2308

2012 ◽  
Vol 194 (18) ◽  
pp. 5065-5072 ◽  
Author(s):  
Clayton C. Caswell ◽  
John E. Baumgartner ◽  
Daniel W. Martin ◽  
R. Martin Roop
Keyword(s):  
Brucella Abortus ◽  
Sequence Similarity ◽  
Mobility Shift ◽  
Organic Hydroperoxide ◽  
Content Type ◽  
Dnase I Footprinting ◽  
Organic Hydroperoxides ◽  
Electrophoretic Mobility Shift Assays

ABSTRACTThe organic hydroperoxide resistance protein Ohr has been identified in numerous bacteria where it functions in the detoxification of organic hydroperoxides, and expression ofohris often regulated by a MarR-type regulator called OhrR. The genes annotated as BAB2_0350 and BAB2_0351 in theBrucella abortus2308 genome sequence are predicted to encode OhrR and Ohr orthologs, respectively. Using isogenicohrandohrRmutants andlacZpromoter fusions, it was determined that Ohr contributes to resistance to organic hydroperoxide, but not hydrogen peroxide, inB. abortus2308 and that OhrR represses the transcription of bothohrandohrRin this strain. Moreover, electrophoretic mobility shift assays and DNase I footprinting revealed that OhrR binds directly to a specific region in the intergenic region betweenohrandohrRthat shares extensive nucleotide sequence similarity with so-called “OhrR boxes” described in other bacteria. While Ohr plays a prominent role in protectingB. abortus2308 from organic hydroperoxide stress inin vitroassays, this protein is not required for the wild-type virulence of this strain in cultured murine macrophages or experimentally infected mice.

scholarly journals Control of Directionality in Bacteriophage mv4 Site-Specific Recombination: Functional Analysis of the Xis Factor

2009 ◽  
Vol 192 (3) ◽  
pp. 624-635 ◽  
Author(s):  
Michèle Coddeville ◽  
Paul Ritzenthaler
Keyword(s):  
Binding Sites ◽  
Basic Protein ◽  
Lactobacillus Delbrueckii ◽  
Mobility Shift ◽  
Site Specific ◽  
Site Specific Recombination ◽  
Dna Binding Sites ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT The integrase of the temperate bacteriophage mv4 catalyzes site-specific recombination between the phage attP site and the host attB site during Lactobacillus delbrueckii lysogenization. The mv4 prophage is excised during the induction of lytic growth. Excisive site-specific recombination between the attR and attL sites is also catalyzed by the phage-encoded recombinase, but the directionality of the recombination is determined by a second phage-encoded protein, the recombination directionality factor (RDF). We have identified and functionally characterized the RDF involved in site-specific excision of the prophage genome. The mv4 RDF, mv4Xis, is encoded by the second gene of the early lytic operon. It is a basic protein of 56 amino acids. Electrophoretic mobility shift assays demonstrated that mv4Xis binds specifically to the attP and attR sites via two DNA-binding sites, introducing a bend into the DNA. In vitro experiments and in vivo recombination assays with plasmids in Escherichia coli and Lactobacillus plantarum demonstrated that mv4Xis is absolutely required for inter- or intramolecular recombination between the attR and attL sites. In contrast to the well-known phage site-specific recombination systems, the integrative recombination between the attP and attB sites seems not to be inhibited by the presence of mv4Xis.

Estrogen-inducible binding of a nuclear factor to the vitellogenin upstream region

1988 ◽  
Vol 8 (10) ◽  
pp. 4557-4560
Author(s):  
O Bakker ◽  
J N Philipsen ◽  
B C Hennis ◽  
G Ab
Keyword(s):  
Dimethyl Sulfate ◽  
Upstream Region ◽  
Nuclear Factor ◽  
Base Pairs ◽  
Exonuclease Iii ◽  
Factor I ◽  
Nuclear Factor I ◽  
Vitellogenin Gene

The estrogen-dependent binding of a protein to the upstream region of the chicken vitellogenin gene was detected by using in vivo dimethyl sulfate, genomic DNase I, and in vitro exonuclease III footprinting. The site is located between base pairs -848 and -824, and its sequence resembles that of the nuclear factor I binding site. The results suggest that a nuclear factor binding to this site is involved in the regulation of the vitellogenin gene.

scholarly journals Newt satellite 2 transcripts self-cleave by using an extended hammerhead structure.

1991 ◽  
Vol 11 (12) ◽  
pp. 6109-6115 ◽  
Author(s):  
L M Pabón-Peña ◽  
Y Zhang ◽  
L M Epstein
Keyword(s):  
Structural Model ◽  
In Vitro Mutagenesis ◽  
Base Pairs ◽  
Site Specific ◽  
Internal Loops

Synthetic transcripts of satellite 2 DNA from newts undergo self-catalyzed, site-specific cleavage in vitro. Cleavage occurs within a domain that is similar to the hammerhead domain used by a number of self-cleaving, infectious plant RNAs. The newt hammerhead has a potentially unstable structure due to a stem composed of two base pairs and a 2-nucleotide loop, and unlike other hammerheads that have been studied, it cannot cleave as an isolated unit. Here we show that cleavage by a single newt hammerhead requires additional satellite 2 sequences flanking both ends of the hammerhead domain. We also present a structural model of a truncated satellite 2 transcript which is capable of cleavage. The structure includes an internally looped extension to one of the conserved stems of the hammerhead. By in vitro mutagenesis, the identities of each of the five nucleotides composing one of the internal loops were shown to be critical for cleavage. Additional evidence that the extension stimulates self-cleavage in a manner other than by simply stabilizing the hammerhead is presented.

scholarly journals TraA and its N-terminal relaxase domain of the Gram-positive plasmid pIP501 show specific oriT binding and behave as dimers in solution

2005 ◽  
Vol 387 (2) ◽  
pp. 401-409 ◽  
Author(s):  
Jolanta KOPEC ◽  
Alexander BERGMANN ◽  
Gerhard FRITZ ◽  
Elisabeth GROHMANN ◽  
Walter KELLER
Keyword(s):  
Amino Acids ◽  
Broad Host Range ◽  
Mobility Shift ◽  
Gram Positive ◽  
Nick Site ◽  
Α Helix ◽  
Electrophoretic Mobility Shift Assays ◽  
Dna Complex ◽  
Β Sheet

TraA is the DNA relaxase encoded by the broad-host-range Grampositive plasmid pIP501. It is the second relaxase to be characterized from plasmids originating from Gram-positive organisms. Full-length TraA (654 amino acids) and the N-terminal domain (246 amino acids), termed TraAN246, were expressed as 6×His-tagged fusions and purified. Small-angle X-ray scattering and chemical cross-linking proved that TraAN246 and TraA form dimers in solution. Both proteins revealed oriTpIP501 (origin of transfer of pIP501) cleavage activity on supercoiled plasmid DNA in vitro. oriT binding was demonstrated by electrophoretic mobility shift assays. Radiolabelled oligonucleotides covering different parts of oriTpIP501 were subjected to binding with TraA and TraAN246. The KD of the protein–DNA complex encompassing the inverted repeat, the nick site and an additional 7 bases was found to be 55 nM for TraA and 26 nM for TraAN246. The unfolding of both protein constructs was monitored by measuring the change in the CD signal at 220 nm upon temperature change. The unfolding transition of both proteins occurred at approx. 42 °C. CD spectra measured at 20 °C showed 30% α-helix and 13% β-sheet for TraA, and 27% α-helix and 18% β-sheet content for the truncated protein. Upon DNA binding, an enhanced secondary structure content and increased thermal stability were observed for the TraAN246 protein, suggesting an induced-fit mechanism for the formation of the specific relaxase–oriT complex.

scholarly journals Transcriptional regulation of Mycobacterium tuberculosis hupB gene expression

Microbiology ◽  
2014 ◽  
Vol 160 (8) ◽  
pp. 1637-1647 ◽  
Author(s):  
Satya Deo Pandey ◽  
Mitali Choudhury ◽  
Manjula Sritharan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Iron Homeostasis ◽  
Iron Concentration ◽  
Dna Interaction ◽  
Intracellular Iron ◽  
Mobility Shift ◽  
Dna Footprinting ◽  
Sequence Of Events ◽  
Electrophoretic Mobility Shift Assays

The influence of iron levels on the transcription of the hupB gene in Mycobacterium tuberculosis is the focus of this study. Studies in our laboratory showed HupB to be co-expressed with the two siderophores in low-iron organisms. Mycobactin biosynthesis is repressed by the IdeR–Fe2+ complex that binds the IdeR box in the mbtB promoter. Recently, we demonstrated the positive regulatory effect of HupB on mycobactin biosynthesis by demonstrating its binding to a 10 bp HupB box in the mbtB promoter. Earlier, we observed that HupB, expressed maximally in low-iron media (0.02 µg Fe ml−1; 0.36 µM Fe) was still detectable at 8 µg Fe ml−1 (144 µM Fe) when the siderophores were absent and complete repression was seen only at 12 µg Fe ml−1 (216 µM Fe). In this study, we observed elevated levels of hupB transcripts in iron-limited organisms. IdeR, and not FurA, functioned as the iron regulator, by binding to two IdeR boxes in the hupB promoter. Interestingly, the 10 bp HupB box, first reported in the mbtB promoter, was identified in the hupB promoter. Using DNA footprinting and electrophoretic mobility shift assays, we demonstrated the functionality of the HupB box and the two IdeR boxes. The high hupB transcript levels expressed by the organism and the in vitro protein–DNA interaction studies led us to hypothesize the sequence of events occurring in response to changes in the intracellular iron concentration, emphasizing the roles played by IdeR and HupB in iron homeostasis.

scholarly journals Gata4 Regulates Testis Expression of Dmrt1

2004 ◽  
Vol 24 (1) ◽  
pp. 377-388 ◽  
Author(s):  
Ning Lei ◽  
Leslie L. Heckert
Keyword(s):  
Transient Transfection ◽  
Mobility Shift ◽  
Specific Expression ◽  
Dnase I Footprinting ◽  
Unknown Factor ◽  
Related Transcription Factor ◽  
Important Regulator ◽  
Functional Relevance ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT The doublesex and mab-3 related transcription factor 1 (Dmrt1) is a putative transcriptional regulator that is expressed exclusively in the gonads and is required for postnatal testis differentiation. Here we describe the transcriptional mechanisms regulating testis-specific expression of the Dmrt1 gene. Transient-transfection analysis identified a region of the promoter between kb −3.2 and −2.8 that is important for Sertoli cell-specific expression. DNase I footprinting revealed four sites of DNA-protein interaction within this region, three of which were prominent in primary Sertoli cells. Analysis of these sites, using electrophoretic mobility shift assays, revealed that Gata4 and another unknown factor bound within these regions. Further transient-transfection assays of various mutant promoters established the functional relevance of the Gata4-response and unknown factor-response elements, while studies of Dmrt1 expression in 13.5 days postcoitum Fog2 null gonads supported the in vivo importance of Gata4's regulation. As a whole, these studies identify Gata4 as an important regulator in the Dmrt1 transcriptional machinery that is responsible for robust expression of Dmrt1 in the testis.

3,5-Diiodo-L-thyronine (T2) has selective thyromimetic effects in vivo and in vitro

1997 ◽  
Vol 19 (2) ◽  
pp. 137-147 ◽  
Author(s):  
SG Ball ◽  
J Sokolov ◽  
WW Chin
Keyword(s):  
Gh3 Cells ◽  
Mrna Levels ◽  
Thyroid Status ◽  
Hormone Activity ◽  
Mobility Shift ◽  
Nuclear Extracts ◽  
Electrophoretic Mobility Shift Assays ◽  
Gh3 Cell

Recent data have suggested that the iodothyronine, 3,5-diiodo-l-thyronine (T2), has selective thyromimetic activity. In vivo, T2 has been shown to suppress TSH levels at doses that do not produce significant peripheral manifestations of thyroid hormone activity. Furthermore, T2 has been shown to produce smaller increments in peripheral indices of thyroid status than does T3, when doses resulting in equivalent suppression of circulating TSH are compared. We have assessed the selective thyromimetic activity of T2 in vivo and in vitro, and performed in vitro studies to assess the potential molecular basis for these selective properties. T2 was 100-fold less potent than T3 in stimulating GH mRNA levels in GH3 cells. In contrast, the iodothyronines were almost equivalent in their ability to downregulate TRbeta2 mRNA levels in this cell line. Both 3,3'-diiodo-L-thyronine and thyronine exhibited no significant thyromimetic effects on either process. In vivo, doses of T2 and T3 that were equivalent in their induction of hepatic malic enzyme (ME) mRNA did not produce equivalent suppression of circulating TSH, with T2 being only 27% as effective as T3. T2 was up to 500-fold less potent than T3 in displacing [125I]-T3 from in vitro translated specific nuclear receptors (TRs) and GH3 cell nuclear extracts. Electrophoretic mobility shift assays, assessing the ability of T2 to produce dissociation of TRbeta1 homodimers from inverted palindrome T3 response elements, indicated that T2 was also 1000-fold less potent than T3 in this respect. These data confirm that T2 has significant thyromimetic activity, and that this activity is selective both in vivo and in vitro. However, there are no data to support a selective central effect, T2 being relatively more potent in stimulating hepatic ME mRNA than in suppression of TSH in vivo. The basis for this differential thyromimetic activity is not selective affinity of the different TR isoforms for T2, or divergent properties of T2 in competitive binding and functional assays in vitro.

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