Hin4II, a new prototype restriction endonuclease from Haemophilus influenzae RFL4: discovery, cloning and expression in Escherichia coli.

The genes encoding restriction-modification system of unknown specificity Hin4II from Haemophilus influenzae RFL4 were cloned in Escherichia coli and sequenced. The Hin4II system comprises three tandemly arranged genes coding for m6A DNA methyltransferase, m5C DNA methyltransferase and restriction endonuclease, respectively. Restriction endonuclease was expressed in E.

Engineering of restriction endonucleases: using methylation activity of the bifunctional endonuclease Eco57I to select the mutant with a novel sequence specificity.

Type II restriction endonucleases (REs) are widely used tools in molecular biology, biotechnology and diagnostics. Efforts to generate new specificities by structure-guided design and random mutagenesis have been unsuccessful so far. We have developed a new procedure called the methylation activity-based selection (MABS) for generating REs with a new specificity.