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Biomedical subjects

C Talkington

Publications and source records attributed to C Talkington.

6 recordsLinked to original sources
PubMed1980

Mouse globin system: a functional and evolutionary analysis.

Structural and functional analysis of the mouse alpha-globin and beta-globin genes reveals that the globin genes are encoded in discontinous bits of coding information and that each gene locus is much more complex than was originally supposed. Each seems to consist of an array of several authentic genes as well as several apparently inactive pseudogenes. Comparison of the sequences of some of these genes to one another indicates that chromosomal DNA is a dynamic structure. Flanking and intervening sequences change in two ways: quickly, by duplication and extensive insertions and deletions, and slowly, by point mutation. Active coding sequences are usually limited to the slower mode of evolution. In addition to identifying fast and slow modes of evolution, it has also been possible to test the function of several signals that surround these genes and to identify those that appear to play a role in gene expression.

Animals↗
PubMed1980

Nucleotide sequence of a promoter recognized by Bacillus subtilis RNA polymerase.

We report the nucleotide sequence of a promoter recognized by RNA polymerase from the gram-positive bacterium Bacillus subtilis. This promoter, which was isolated from B. subtilis phage SP01 DNA, is homologous to promoters for Escherichia coli RNA polymerase; the sequences of the "-35 region" and the "Pribnow box" were 5'TTGACT and 5'CATAAT, respectively (T is the thymine analog 5-hydroxymethyluracil in SP01 DNA). These sequences each differed by only a single base pair from the preferred sequences for E. coli promoters. Not surprisingly, the SP01 promoter was actively transcribed in vitro by E. coli RNA Polymerase as well as by B. subtilis RNA polymerase.

Bacillus subtilis↗
PubMed1979

Distinctive nucleotide sequences of promoters recognized by RNA polymerase containing a phage-coded "sigma-like" protein.

We report the nucleotide sequences of two promoters for bacteriophage SP01 "middle" genes. These promoters are recognized by a modified form of Bacillus subtilis RNA polymerase that contains a phage-coded "sigma-like" regulatory protein (gp28) in place of the bacterial sigma factor. Both promoters shared the identical hexanucleotide 5'A-G-G-A-G-A at about 35 base pairs preceding the start point of transcription and the identical heptanucleotide 5'-T-T-T-A-T-T-T (T is the thymine analog 5-hydroxymethyluracil in SP01 DNA) located about 10 base pairs preceding the transcriptional start point. The significance of these sequences in comparison with nucleotide sequences of promoters recognized by sigma-containing RNA polymerases is discussed.

Bacillus subtilis↗
PubMed1979

Restriction cleavage map of SP01 DNA: general location of early, middle, and late genes.

A detailed restriction endonuclease map for the genome of Bacillus subtilis phage SP01 is presented. Sites of cleavage for the restriction enzymes BglII, EcoRI, HaeIII, and SalI were determined. This physical map showed that SP01 DNA was 140 kilobases in length and contained a repeated sequence of 12.4 kilobases at its termini. Combined with previously published information, we were also able to identify the general locations of genes expressed at early, middle, or late times in the phage lytic cycle. In particular, early genes were largely clustered in the terminal repeats, whereas a major cluster of late genes was located in the left-central portion of the genome.

Bacillus subtilis↗
PubMed1978

Promoter recognition by phage SP01-modified RNA polymerase.

A modified form of Bacillus subtilis RNA polymerase containing a phage SP01-coded regulatory protein (the gene 28 product) selectively transcribes "middle" genes of the phage genome in vitro. In this paper, we identify a subset of restriction endonuclease fragments of SP01 DNA that promote specific transcription by the phage-modified polymerase. In the absence of nucleoside triphosphates, RNA polymerase containing the gene 28 protein selectively binds to these DNA fragments thereby forming stable binary complexes that can be isolated on nitrocellulose filters. In contrast, unmodified RNA polymerase containing sigma factor selectively binds to and transcribes a subset of phage DNA fragments that contain "early" sequences and that are in large part distinct from the fragments recognized by the phage-modified transcriptase. Our results strongly suggest that phage "early" and "middle" genes are transcribed from distinct promoters and that the RNA polymerase containing the gene 28 protein binds to sites that are located at or near promoters for SP01 "middle" genes.

Bacillus subtilis↗