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K A Jones

Publications and source records attributed to K A Jones.

135 records · Page 8Linked to original sources
PubMed1985

Two distinct transcription factors bind to the HSV thymidine kinase promoter in vitro.

We have characterized an in vitro transcription system derived from uninfected HeLa cells that accurately initiates RNA synthesis at the herpes virus thymidine kinase (TK) promoter. Analysis of linker-scanning, single-site, and promoter-inversion mutants reveals that the TK upstream elements previously mapped in vivo are accurately recognized in vitro. A protein fraction required for TK transcription in reconstitution experiments was found to contain multiple protein species that bind specifically to the TK promoter. DNAase I footprint experiments with wild-type and mutant promoters reveal that the TK upstream elements contain three distinctive protein binding sites, two of which appear to be recognized by the Sp1 transcription factor and one which interacts with a cellular protein that binds to "CCAAT" sequences. Optimal expression of the thymidine kinase gene appears to require the coordinate interaction of these two types of transcription factors with the three upstream elements of the promoter.

Base Sequence↗
PubMed1984

Mutational analysis of simian virus 40 large T antigen DNA binding sites.

We have tested the effects of various mutations within SV40 T antigen DNA recognition sites I and II on specific T antigen binding using the DNase footprint technique. In addition, the replication of plasmid DNA templates carrying these T antigen binding site mutations was monitored by Southern analysis of transfected DNA in COS cells. Deletion mapping of site I sequences defined a central core of approximately 18 bp that is both necessary and sufficient for T antigen recognition; this region contains the site I contact nucleotides that were previously mapped using methylation-interference and methylation-protection experiments. A similar deletion analysis delineated sequences that impart specificity of binding to site II. We find that T antigen is capable of specific recognition of site II in the absence of site I sequences, indicating that binding to site II in vitro is not dependent on binding of T antigen at site I. Site II binding was not diminished by small deletion or substitution mutations that perturb the 27-bp palindrome central to binding site II, whereas extensive substitution of site II sequences completely eliminated specific site II binding. Analysis of the replication in COS7 cells of plasmids that contain these mutant origins revealed that sequences both at the late side of binding site I and within the site II palindrome are crucial for viral DNA replication, but are not involved in binding T antigen.

Antigens, Viral, Tumor↗
PubMed1984

Temperature dependent attraction by goldfish to a chemical feeding cue presented alone and in combination with heated water.

An eight cell multiple-choice experiment was used to investigate the influence of temperature on the locomotor response of goldfish (Carassius auratus) to a chemical feeding cue. When a food extract was infused into a single cell at ambient temperatures of 26, 28, 30, 32, and 34 degrees C (ambient temperature=acclimation temperature) the goldfish spent more time in the extract cell than three similarly outfitted dummy cells at all temperatures, but the intensity of their attraction varied over the thermal interval. Attraction was highest at 28 degrees C and gradually declined to its lowest level by 34 degrees C. Goldfish acclimated and tested at 26 degrees C spent more time visiting a combination of food extract and heated water (H+E) than either food extract (E) or heated water (H) alone. The preference for H+E over H and E increased with the temperature differential between heated and ambient waters. Successive increased in acclimation/ambient temperature (30, 32, and 34 degrees C) extinguished the differences between H+E and H and E but did not eliminate the attraction for the thermal and chemical stimuli, per se. The importance of temperature in the variability of chemoreceptive behavior and the interaction between chemical and thermal stimuli are discussed.

Animals↗
PubMed1984

Essential contact residues within SV40 large T antigen binding sites I and II identified by alkylation-interference.

Essential nucleotide contacts between the SV40 large T (tumor) antigen and binding sites I and II on the SV40 genome have been inferred from in vitro methylation- and ethylation-interference experiments. Each site contains two clusters of guanine residues that reduce the specific binding of T antigen when modified. Methylation at any one of nine guanines within site I or any one of five guanines within site II severely interferes with the interaction of T antigen with each respective site. Methylation at any one of a second group of five guanines within site II results in an appreciably weaker effect on the binding of T antigen. A similar inhibitory effect on binding is observed upon ethylation of adjacent phosphate residues. Although there are significant differences in the nucleotide sequence of the two binding sites, the pattern of protein contacts is strikingly similar between sites I and II. Three-dimensional projection reveals that the guanine contacts within each binding site are localized so that the specific binding interactions are accessible from only one face of the DNA helix.

Alkylation↗
PubMed1983

Reversibility characteristics of glucose-induced trehalase activation associated with the breaking of dormancy in yeast ascospores.

The breaking of dormancy in yeast ascospores by addition of glucose is associated with a sudden tenfold increase in the activity of trehalase. The rapid activation of trehalase is followed by a slower inactivation process which is greatly retarded in the presence of nitrogen sources and cycloheximide. When glucose is washed away from the spores after some time and the spores resuspended in glucose-free medium, the trehalase activity decreases sharply. Subsequent addition of new glucose partially reactivates the enzyme. The extent of reactivation decreases further with each subsequent activation/inactivation step. Changing the duration of the inactivation periods has no effect on this diminution of the reversibility. However, prolonging the duration of the activation step speeds up the loss of reversibility. On the other hand, addition of a nitrogen source or cycloheximide completely prevents the loss of reversibility. The results of the reversibility studies are in agreement with the phosphorylation mechanism which has been proposed for the underlying molecular process of trehalase activation. Apparently, they are also in agreement with proteolytic breakdown being responsible for the inactivation of trehalase after its initial activation. However, the effect of cycloheximide and nitrogen sources, at least in ascospores, does not appear to be due to inhibition or repression of protease synthesis, respectively, since the addition in the presence of glucose of a nitrogen source after trehalase inactivation immediately reactivates the enzyme completely.

Ascomycota↗
PubMed1983

Differential backfilling of interneuron populations based upon axon projections in a lobster abdominal ganglion.

Intersegmental interneurons in the lobster second abdominal ganglion were differentially stained by simultaneously backfilling their axons in the anterior and posterior hemiconnectives with nickel and cobalt ions. When precipitated with rubeanic acid the nickel and cobalt formed different colors in the cell bodies depending upon the location of the axon(s) in the connectives. In the most completely stained preparations 55 ascending, 56 descending, and 25 bidirectional interneurons were observed. Soma diameters ranged from 15-120 micron. One of the somata was located in the connective. The differential staining technique has advantages over conventional backfilling techniques for examining the morphological relationships of populations of neurons having different axon projections.

Animals↗
PubMedDate not supplied

Sp1 binds to promoter sequences and activates herpes simplex virus 'immediate-early' gene transcription in vitro.

During a herpes simplex virus (HSV-1) lytic infection, three classes of viral genes are transcribed in a temporally regulated manner. The HSV-1 'immediate-early' (IE) promoter sequences contain multiple copies of a hexanucleotide sequence, GGGCGG, known as a GC box, and one or more copies of an 11-base pair (bp) conserved A + T-rich element, designated TAATGARAT. The TAATGARAT elements are thought to mediate the trans-activation of IE RNA synthesis by a virion-associated protein(s), and the flanking G + C-rich sequences appear both to potentiate this induction and to direct IE promoter activity in vivo. The similarity of the herpesvirus GC box repeats to those of the simian virus 40 (SV40) early promoter prompted the in vitro analysis of HSV IE transcription reported here. We show that the mammalian gene-specific transcription factor Sp1 binds to eight distinct regions of the HSV short terminal repeat and stimulates transcription 25-fold from the divergent IE-3 (ICP-4) and IE-4/5 promoters.

Binding Sites↗
PubMedDate not supplied

Regulation of BRCA1.

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BRCA1 Protein↗