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Biomedical subjects

Allan Campbell

Publications and source records attributed to Allan Campbell.

5 recordsLinked to original sources
PubMed2003

Prophage insertion sites.

Insertion of viral DNA into host chromosomes is an ancient process essential for propagation in the proviral form. Many present-day bacteriophages insert at specific sites on the host chromosome. Insertion by two coliphage families (lambdoid and P4-like) is compared. For both families, insertion sites frequently lie within tRNA genes. The lambdoid phages insert at anticodon loops, whereas the p4-like phages insert in the TpsiC loops downstream from them. The association of both groups with tRNA genes suggests that the primordial insertion site of both groups may have been within a tRNA gene. The integrase proteins used in phage insertion may have originated at that stage, with subsequent diversification of specificity.

Attachment Sites, Microbiological↗
PubMed2003

The future of bacteriophage biology.

After an illustrious history as one of the primary tools that established the foundations of molecular biology, bacteriophage research is now undergoing a renaissance in which the primary focus is on the phages themselves rather than the molecular mechanisms that they explain. Studies of the evolution of phages and their role in natural ecosystems are flourishing. Practical questions, such as how to use phages to combat human diseases that are caused by bacteria, how to eradicate phage pests in the food industry and what role they have in the causation of human diseases, are receiving increased attention. Phages are also useful in the deeper exploration of basic molecular and biophysical questions.

Bacteria↗
PubMed2002

Specificity in DNA recognition by phage integrases.

The lambda-related (lambdoid) coliphages are related to one another by frequent natural recombination and maintain a high level of functional polymorphism for several activities of the phages. Arguments are presented that the polymorphism of the integration module results from selection (presumably frequency-dependent) for new (not improved) specificities of site recognition. Analysis of phages lambda and HK022 by Weisberg and collaborators previously showed that changes in five noncontiguous amino acids could switch site recognition specificity. Phage 21 and defective element e14, which integrate at the same site, differ in recognition specificity for both core and arm sites. In vitro assays of e14 and 21 insertion and excision confirm this conclusion. Inhibition by ds arm site oligonucleotides defines the sequence specificity more precisely.

Bacteriophage lambda↗
PubMed2002

Correlations between Shine-Dalgarno sequences and gene features such as predicted expression levels and operon structures.

This work assesses relationships for 30 complete prokaryotic genomes between the presence of the Shine-Dalgarno (SD) sequence and other gene features, including expression levels, type of start codon, and distance between successive genes. A significant positive correlation of the presence of an SD sequence and the predicted expression level of a gene based on codon usage biases was ascertained, such that predicted highly expressed genes are more likely to possess a strong SD sequence than average genes. Genes with AUG start codons are more likely than genes with other start codons, GUG or UUG, to possess an SD sequence. Genes in close proximity to upstream genes on the same coding strand in most genomes are significantly higher in SD presence. In light of these results, we discuss the role of the SD sequence in translation initiation and its relationship with predicted gene expression levels and with operon structure in both bacterial and archaeal genomes.

Archaeal Proteins↗