In response to an external source of adenine, yeast cells repress the expression of purine biosynthesis pathway genes. To identify necessary components of this signalling mechanism, we have isolated mutants that are constitutively active for expression. These mutants were named bra (for bypass of repression by adenine). BRA7 is allelic to FCY2, the gene encoding the purine cytosine permease and...

The radiation-induced biological behavior of adenine (vitamin B4) was investigated in vitro under various conditions, implementing breast cancer cells (MCF-7 line) as a model. In aerated media (46% OH and 54% O2*-) at pH=7.4, adenine at low concentration (2 micromol) acted as an efficient radiation-protecting agent. At higher concentration, however, it inhibited cytostatic properties with regar...

Riboswitches are RNA-based genetic control elements that function via a conformational transition mechanism when a specific target molecule binds to its binding pocket. To facilitate an atomic detail interpretation of experimental investigations on the role of the adenine ligand on the conformational properties and kinetics of folding of the add adenine riboswitch, we performed molecular dynami...

The adenine nucleotide content of the 2-centimeter segments excised from tray-grown corn (Zea mays L., WF9 x Mo17) roots declines for the first hour after excision. Concomitant with the loss of adenine nucleotides is a decline in respiration and a leakage of K(+). With continued washing, these parameters partially or completely recover and increased phosphate influx develops. Increasing the wou...

GRP94, the endoplasmic reticulum paralog of hsp90, has recently been identified as a peptide and adenine nucleotide-binding protein. To determine if adenine nucleotides directly contribute to the regulation of GRP94 peptide binding activity, an in vitro peptide binding assay was developed. Using purified GRP94, we observed specific, saturable, temperature-sensitive binding of the peptide VSV8, ...

The effect of sodium fluoride on the content of adenine nucleotides, adenine nucleotide pool and energy potential of erythrocytes was studied in male Wistar rats, depending on the dose and time of exposure. Sodium fluoride was administered for 4 and 8 weeks at 4 or 16 ppm through a gastric tube. The concentration of fluorine in serum, ATP, ADP and AMP content in blood and erythrocytes, adenine ...

The AG dinucleotide at the 3' splice sites of metazoan nuclear pre-mRNAs plays a critical role in catalytic step II of the splicing reaction. Previous studies have shown that replacement of the guanine by adenine in the AG (AG --> GG) inhibits this step. We find that the second step was even more severely inhibited by cytosine (AG --> CG) or uracil (AG --> UG) substitutions at this position. By...

The mechanism of the photodimerization of adjacent adenine bases on the same strand of DNA has been elucidated by determining the structure of one of the two major photoproducts that are formed by UV irradiation of the deoxydinucleoside monophosphate d(ApA). The photoproduct, denoted d(ApA)*, corresponds to a species of adenine photodimer first described by Pörschke (Pörschke, D. (1973) J.Am.Ch...

Gene activation in eukaryotes is inherently combinatorial depending on cooperation between different transcription factors. An example where this cooperation seems to be directly exploited for regulation is the Bas1p/Bas2p couple in yeast. Bas1p is a Myb-related transcription factor that acts together with the homeodomain-related Bas2p (Pho2p) to regulate purine and histidine biosynthesis genes...

Chemically synthesized duplex oligodeoxynucleotides having different average numbers of adenine tracts (A6) per helix turn were ligated into multimers and analyzed by electrophoresis on polyacrylamide gels. The magnitude of the anomaly in gel mobility is found to be a quadratic function of the curvature of the DNA molecule. Parameters that describe intrinsic DNA bending, expressed as the tilt a...