Nucleases: diversity of structure, function and mechanism

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Nucleases are essential enzymes that cleave phosphodiester bonds in nucleic acids.
• They exhibit diverse activities including endonuclease, exonuclease, DNase, RNase, topoisomerase, and recombinase functions.
• Their roles span critical cellular processes such as DNA replication, repair, and RNA processing.

Purpose of the Study:

• To review and classify nuclease activities based on structural, catalytic, and functional properties.
• To analyze the relationship between nuclease catalytic mechanisms, metal-ion dependence, and biological functions.
• To identify overarching principles governing nuclease diversity and evolution.

Main Methods:

• Systematic survey of nucleases with known structures and catalytic mechanisms.
• Classification of nucleases by reaction mechanism, metal-ion dependence, and biological function.
• Comparative analysis of catalytic strategies across different nuclease families.

Main Results:

• Little correlation exists between a nuclease's catalytic mechanism and its biological function.
• A single catalytic mechanism can support diverse biological pathways, and vice versa.
• Two-metal-ion-dependent nucleases represent the largest group, mediating the most varied functions.
• Distinct cleavage products and intermediates characterize metal-ion-dependent versus metal-ion-independent nucleases.

Conclusions:

• Nuclease catalytic strategies are highly adaptable and convergent.
• The diversity of nuclease folds and functions highlights evolutionary flexibility.
• Shared catalytic configurations suggest previously unrecognized evolutionary relationships among nucleases.