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Studies on the heterologous expression of BstVI restriction endonuclease in Escherichia coli
Author(s) -
Saavedra Claudia,
González Enrique,
Vásquez Claudio
Publication year - 1998
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549800201402
Subject(s) - extrachromosomal dna , biology , endonuclease , escherichia coli , restriction enzyme , genetics , heterologous , temperateness , dna , microbiology and biotechnology , methyltransferase , gene , plasmid , methylation , bacteriophage
Bacterial restriction and modification systems must be regulated to avoid self‐restriction. It is generally accepted that cognate DNA methyltransferases normally protects both, the host's chromosome and extrachromosomal elements from the activity of their endonuclease counterparts. When the bstVIRM genes from Bacillus stearothermophilusV were subcloned into Escherichia coli, several clones exhibiting a r+m‐ phenotype were originated. The present work was undertaken to analyze the possibility that mechanisms other than DNA methylation could account for the viability of these cells. No evidence was found for an inhibitory agent or endonuclease compartmentation. In vivo experiments showed that λ phage multiplication was poorly restricted by the heterologous enzyme. The restricting activity against the incoming phage increased however when phage adsortion was performed at higher temperatures. Analogous experiments in which a DNA‐repair deficient strain was used as a host for the thermophilic R‐M system suggested, to some extent, the participation of the repair machinery in the viability of r+m‐ clones.