ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 4 | 4 hits

Sorting

Electronic Resource

Activation of enteropathogenic Escherichia coli (EPEC) LEE2 and LEE3 operons by Ler (2000)

Sperandio, Vanessa ; Mellies, Jay L. ; Delahay, Robin M. ; [et al.]

Oxford, UK : Blackwell Science, Ltd

Molecular microbiology 38 (2000), S. 0

add to mindlist on the mindlist

Details

ISSN: 1365-2958

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Medicine

Notes: Enteropathogenic Escherichia coli (EPEC) produces attaching and effacing lesions (AE) on epithelial cells. The genes involved in the formation of the AE lesions are contained within a pathogenicity island named the locus of enterocyte effacement (LEE). The LEE comprises 41 open reading frames organized in five major operons: LEE1, LEE2, LEE3, LEE4 and tir. The first gene of the LEE1 operon encodes a transcription activator of the other LEE operons that is called the LEE-encoded regulator (Ler). The LEE2 and LEE3 operons are divergently transcribed with overlapping −10 promoter regions, and gene fusion studies have shown that they are both activated by Ler. Deletion analysis, using lacZ reporter fusions, of the LEE2 and LEE3 promoters demonstrated that deletions extending closer to the LEE2 transcription start site than −247 bp lead to loss of activation by Ler, whereas only 70 bp upstream of the LEE3 transcription start site is required for Ler-mediated activation. We have purified Ler as a His-tagged protein and used it to perform DNA-binding assays with LEE2 and LEE3. We observed that Ler bound to a DNA fragment containing the −300 to +1 region of LEE2; however, it failed to bind to a DNA fragment containing the −300 to +1 region of LEE3, suggesting that Ler activates both operons by only binding to the regulatory region upstream of LEE2. The Ler-activatable LEE3::lacZ fusions extended to what would be −246 bp of the LEE2 operon. A lacZ fusion from the −300 to +1 region of LEE3 failed to be activated by Ler, consistent with our hypothesis that Ler activates the expression of LEE2 and LEE3 by binding to a region located downstream of the LEE3 transcription start site. DNase I footprinting revealed that Ler protected a region of 121 bp upstream of LEE2. Purified Ler mutated in the coiled-coil domain was unable to activate transcription and to bind to the LEE2 regulatory region. These data indicate that Ler may bind as a multimer to LEE2 and activate both divergent operons by a novel mechanism potentially involving changes in the DNA structure.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02168.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Increased T-type Ca2+ channel activity as a determinant of cellular toxicity in neuronal cell lines expressing polyglutamine-expanded human androgen receptors (2000)

Sculptoreanu, Adrian ; Abramovici, Hanan ; Abdullah, Abdullah A.R. ; [et al.]

Springer

Molecular and cellular biochemistry 203 (2000), S. 23-31

add to mindlist on the mindlist

Details

ISSN: 1573-4919

Keywords: T-type Ca2+ channel ; polyglutamine-expanded androgen receptor ; CAG trinucleotide repeats ; spinobulbar muscular atrophy ; apoptosis ; motorneuron ; cell lines ; neuroblastoma

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Medicine

Notes: Abstract We have analyzed Ca2+ currents in two neuroblastoma-motor neuron hybrid cell lines that expressed normal or glutamine-expanded human androgen receptors (polyGln-expanded AR) either transiently or stably. The cell lines express a unique, low-threshold, transient type of Ca2+ current that is not affected by L-type Ca2+ channel blocker (PN 200-110), N-type Ca2+ channel blocker (ω-conotoxin GVIA) or P-type Ca2+ channel blocker (Agatoxin IVA) but is blocked by either Cd2+ or Ni2+. This pharmacological profile most closely resembles that of T-type Ca2+ channels [1-3]. Exposure to androgen had no effect on control cell lines or cells transfected with normal AR but significantly changed the steady-state activation in cells transfected with expanded AR. The observed negative shift in steady-state activation results in a large increase in the T-type Ca2+ channel window current. We suggest that Ca2+ overload due to abnormal voltage-dependence of transient Ca2+ channel activation may contribute to motor neuron toxicity in spinobulbar muscular atrophy (SBMA). This hypothesis is supported by the additional finding that, at concentrations that selectively block T-type Ca2+ channel currents, Ni2+ significantly reduced cell death in cell lines transfected with polyGln-expanded AR.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1007010020228

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

A new spontaneous mouse mutation in the Kcne1 gene (2000)

Letts, V.A. ; Valenzuela, A. ; Dunbar, C. ; [et al.]

Springer

Mammalian genome 11 (2000), S. 831-835

add to mindlist on the mindlist

Details

ISSN: 1432-1777

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract. A new mouse mutant, punk rocker (allele symbol Kcne1 pkr ), arose spontaneously on a C57BL/10J inbred strain background and is characterized by a distinctive head-tossing, circling, and ataxic phenotype. It is also profoundly and bilaterally deaf. The mutation resides in the Kcne1 gene on Chromosome (Chr) 16 and has been identified as a single base change within the coding region of the third exon. The C to T nucleotide substitution causes an arginine to be altered to a termination codon at amino acid position 67, and predictably this will result in a significantly truncated protein product. The Kcne1 pkr mutant represents the first spontaneous mouse model for the human disorder, Jervell and Lange-Nielsen syndrome, associated with mutations in the homologous KCNE1 gene on human Chr 21.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003350010178

Permalink