His-Me finger (also called HNH or ββα-me) nucleases, are a large superfamily of nucleases that share limited sequence homology, but all members carry a highly similar catalytic motif exhibiting a ββα topology. This review represents a structural comparison of His-Me finger nucleases, summarizing their substrate-binding and recognition strategies, mechanisms of enzymatic hydrolysis, cellular functions, and the various means of activity regulation. His-Me finger nucleases usually function as monomers, making a single nick in nucleic acids to degrade foreign or host genomes, or as homodimers that introduce double-stranded DNA breaks for DNA restriction, integration, recombination, and repair. Various cellular neutralizing machineries have evolved to regulate the activity of His-Me finger nucleases, thereby maintaining genome integrity and cellular functionality.
Keywords: DNA cleavage; DNA hydrolysis; DNase; HNH family.
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