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H E Wood

Publications and source records attributed to H E Wood.

4 recordsLinked to original sources
PubMed1990

Characterisation of a repressor gene (xre) and a temperature-sensitive allele from the Bacillus subtilis prophage, PBSX.

The defective prophage of Bacillus subtilis 168, PBSX, is a chromosomally based element which encodes a non-infectious phage-like particle with bactericidal activity. PBSX is induced by agents which elicit the SOS response. In a PBSX thermoinducible strain which carries the xhi1479 mutation, PBSX is induced by raising the growth temperature from 37 degrees C to 48 degrees C. A 1.2-kb fragment has been cloned which complements the xhi1479 mutation. The nucleotide sequence of this fragment contains an open reading frame (ORF) which encodes a protein of 113 amino acids (aa). This aa sequence resembles that of other bacteriophage repressors and suggests that the N-terminal region forms a helix-turn-helix motif, typical of the DNA-binding domain of many bacterial regulatory proteins. The ORF is preceded by four 15-bp direct repeats, each of which contains an internal palindromic sequence, and by sequences resembling a SigA-dependent promoter. The nt sequence of an equivalent fragment from the PBSX thermoinducible strain has also been determined. There are three aa differences within the ORF compared to the wild type, one of which lies within the helix-turn-helix segment. This ORF encodes a repressor protein of PBSX.

Amino Acid Sequence↗
PubMed1990

Superoxide radical production after phorbol ester stimulation in neutrophils of aged donors.

Superoxide anion radical production was studied in purified neutrophils of young and old donors after stimulation with phorbol 12-myristate 13-acetate to determine whether phorbol-stimulated activation of NADPH-oxidase was altered by aging. Superoxide radical production of neutrophils of healthy ambulatory elderly (mean age 73 years) was increased compared to young adult controls. Expressed as nmol superoxide/min/mg protein, however, old cells were no different from young. Neutrophils of the elderly contained nearly 20% more protein/cell than young cells, yet neutrophil diameter and volume were not increased in the old cells. Binding affinity and maximum binding capacity of 3H-phorbol 12,13-dibutyrate were similar in young and old neutrophils. Maximum binding capacity was similar whether expressed on a per cell or per mg protein basis. Although others have suggested that initial plasma membrane events leading to superoxide radical production are diminished in aging cells, these studies show that intracellular phases of the mechanisms leading to superoxide radical production are maintained. Superoxide production rate per cell is increased in older persons, associated with a higher protein content per cell but not larger cell size.

Adult↗
PubMed1990

Characterization of PBSX, a defective prophage of Bacillus subtilis.

PBSX, a defective Bacillus subtilis prophage, maps to the metA-metC region of the chromosome. DNA (33 kilobases) from this region of the chromosome was cloned and analyzed by insertional mutagenesis with the integrating plasmid pWD3. This plasmid had a promoterless alpha-amylase gene (amyL) that provided information on the direction and level of transcription at the site of integration. Transcription under the control of the PBSX repressor proceeded in the direction metA to metC over a distance of at least 18 kilobases. Electrophoretic analysis of proteins produced by different integrant strains upon PBSX induction and by fragments subcloned in Escherichia coli allowed the identification of early and late regions of the prophage. A set of contiguous fragments directing mutagenic integration suggested that the minimum size of an operon that encodes phage structural proteins is 19 kilobases. The adaptation of PBSX transcriptional and replicational functions to a chromosomally based, thermoinducible expression system is discussed.

Bacillus subtilis↗