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30 results on '"Schultz, Steve C."'

9. Modulation of telomerase activity by telomere DNA-binding proteins in Oxytricha

Author

Froelich-Ammon, Stacie J., Dickinson, Brent A., Bevilacqua, Joanne M., Schultz, Steve C., and Cech, Thomas

Subjects
Telomeres -- Research, DNA binding proteins -- Research, Protozoa -- Research, Biological sciences
Abstract

The single-stranded telomere DNA binding-protein in the protozoan Oxytricha inhibits telomerase and contributes to maintaining the length of the telomere by making telomeric DNA inaccessible. The protein has alpha and beta subunits that can displace telomerase because of their greater affinity for the DNA. The alpha subunit apparently plays a role in length regulation. Moreover, the alpha-beta-DNA complex does not act as a substrate for terminal deoxynucleotidyltransferase.

Published
1998

15. Novel syn intramolecular pathway in base-catalyzed 1,2-elimination reactions of beta-acetoxy esters

Author

Mohrig, Jerry R., Carlson, Hans K., Coughlin, Jane M., Hofmeister, Gretchen E., McMartin, Lea A., Rowley, Elizabeth G., Trimmer, Elizabeth E., Wild, Andrew J., and Schultz, Steve C.

Subjects
Acetic acid -- Electric properties, Acetic acid -- Chemical properties, Stereochemistry -- Analysis, Biological sciences, Chemistry
Abstract

Study was conducted to show a new syn intramolecular pathway in the elimination of acetic acid from beta-acetoxy esters and thioesters as a part of a comprehensive investigation of electronic effects on the stereochemistry of based-catalyzed 1,2-elimination reactions. Results show that more acidic thioester substrates do not produce an increased amount of syn stereoselectivity even though their elimination reactions are at the Elcb interface.

Published
2007

16. Sequence-specific and 3'-end selective single-strand DNA binding by the Oxytricha nova telomere end binding protein alpha subunit

Author

Classen, Scott, Lyons, Dan, Cech, Thomas, and Schultz, Steve C.

Subjects
Binding proteins -- Physiological aspects, DNA-ligand interactions -- Physiological aspects, DNA-ligand interactions -- Analysis, Telomeres -- Physiological aspects, Nucleoproteins -- Research, Biological sciences, Chemistry
Abstract

Research shows that addition of nucleotides to the 3'-end of the telomere repeat from Oxytricha nova decreases alpha binding 7-fold indicating specificity of 3'-terminus to DNA binding sites. Nucleotide substitutions at designated sites within the telomere repeat cause reductions in binding affinity by less that 2-fold to more than 20-fold.

Published
2003

26. Creation of a test plasmid for detecting G-C-to-T-A transversions by changing serine to arginine in the active site of beta-lactamase

Author

Foster, Patricia L., Dalbadie-McFarland, Gloria, Davis, Elaine F., Schultz, Steve C., Richards, John H., Foster, Patricia L., Dalbadie-McFarland, Gloria, Davis, Elaine F., Schultz, Steve C., and Richards, John H.

Abstract

Oligonucleotide-directed mutagenesis of the beta-lactamase gene, bla, on pBR322 was used to change the codon for the active-site serine 70, AGC, to CGC, coding for arginine. Escherichia coli cells carrying the mutant plasmid, pGD104, were sensitive to ampicillin, indicating that the arginine-containing enzyme is inactive. We characterized the reversion of the mutant bla gene by a number of mutagens and in different genetic backgrounds and demonstrated that full ampicillin resistance can be restored only by a G-C-to-T-A transversion occurring at the first base of the codon. Thus, reversion of the mutant bla gene is diagnostic for G-C-to-T-A transversions, and bacteria carrying pGD104 can be used as test strains to detect the occurrence of this mutation.

Published
1987

30. Dimeric structure of the Oxytricha nova telomere end-binding protein alpha-subunit bound to ssDNA.

Author

Peersen OB, Ruggles JA, and Schultz SC

Subjects
Animals, Base Sequence, Binding Sites, Crystallography, X-Ray, DNA, Single-Stranded genetics, Dimerization, Models, Molecular, Nucleic Acid Conformation, Protein Binding, Protein Structure, Tertiary, Protein Subunits, Protozoan Proteins chemistry, Protozoan Proteins metabolism, Repetitive Sequences, Nucleic Acid genetics, Telomere genetics, DNA, Single-Stranded chemistry, DNA, Single-Stranded metabolism, DNA-Binding Proteins chemistry, DNA-Binding Proteins metabolism, Oxytricha chemistry, Oxytricha genetics, Telomere chemistry, Telomere metabolism
Abstract

Telomeres are the specialized protein--DNA complexes that cap and protect the ends of linear eukaryotic chromosomes. The extreme 3' end of the telomeric DNA in Oxytricha nova is bound by a two-subunit sequence-specific and 3' end-specific protein called the telomere end-binding protein (OnTEBP). Here we describe the crystal structure of the alpha-subunit of OnTEBP in complex with T4G4 single-stranded telomeric DNA. This structure shows an (alpha--ssDNA)2 homodimer with a large approximately 7,000 A2 protein--protein interface in which the domains of alpha are rearranged extensively from their positions in the structure of an alpha--beta--ssDNA ternary complex. The (alpha--ssDNA)2 complex can bind two telomeres on opposite sides of the dimer and, thus, acts as a protein mediator of telomere--telomere associations. The structures of the (alpha--ssDNA)2 dimer presented here and the previously described alpha--beta--ssDNA complex demonstrate that OnTEBP forms multiple telomeric complexes that potentially mediate the assembly and disassembly of higher order telomeric structures.

Published
2002
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