Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of ampicillin-resistant strains of Haemophilus influenzae could donate a gene specifying the type IIIa (TEM) beta-lactamase to Haemophilus parainfluenzae, Escherichia coli, and Pseudomonas aeruginosa. Donor strains rapidly lost their ability to transfer ampicillin resistance on storage or subculture. Such strains also apparently contained a single species of covalently closed circular deoxyribonucleic acid of contour length 1.2 mum, equivalent to about 2.5 x 10(6) daltons. No species of plasmid deoxyribonucleic acid large enough to encode sex factor activity was detected. Despite this, transfer occurred to several bacterial genera in the presence of deoxyribonuclease, suggesting that transmissibility was by conjugation. The beta-lactamase gene was generally unstable after transfer and was lost in the absence of selection. Where stable transcipients were found, this was evidently by insertion of the beta-lactamase gene into the host chromosome. In P. aeruginosa insertion was always accompanied by induction of auxotrophy for adenine, suggesting insertion at a specific site. It is believed that insertion also occurred at one site on the chromosome of Escherichia coli. Crypticity measurements for beta-lactamase activity showed that there was little or no penetration barrier to beta-lactam drugs in Haemophilus. This may explain the long delay in the acquisition of ampicillin resistance by this organism.
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PMID:Transfer of a plasmid-specified beta-lactamase gene from Haemophilus influenzae. 40 56

A series of C-terminal deletions of the dns-encoded extracellular deoxyribonuclease (DNS) of Vibrio cholerae, fused to the mature form TEM beta-lactamase (Bla) has been used to analyse the export of the DNase in both V. cholerae and Escherichia coli. All hybrid proteins were localized to the periplasmic space in E. coli and V. cholerae, with specific cleavage of the DNS-Bla fusion occurring in V. cholerae. Periplasmic accumulation of wt DNS was also seen in V. cholerae when present on a multicopy plasmid. DNS fusions retaining all six Cys residues of DNS displayed both DNase and Bla enzymatic activity. While hybrid proteins were unable to be secreted across the outer membrane in V. cholerae, the cleaved (active) DNS portion of these proteins was exported. Taken together, these data suggest that the periplasmic form seen in E. coli is a normal intermediate also seen in V. cholerae, and that the lack of secretion machinery in E. coli prevents further export across the outer membrane. Although the DNS portion of the protein fusions must be able to interact with secretion genes, the whole fusion proteins are not exported.
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PMID:Genetic analysis of the export of an extracellular DNase of Vibrio cholerae using DNase-beta-lactamase fusions. 176 Dec 28