Cytosine-specific type II DNA methyltransferases. A conserved enzyme core with variable target-recognizing domains

Area of Science:

• Molecular Biology
• Biochemistry
• Enzymology

Background:

• DNA methyltransferases (Mtases) are crucial enzymes involved in DNA modification.
• These enzymes exhibit conserved structural features across different organisms.
• Previous research identified target-recognizing domains (TRDs) within multispecific phage Mtases.

Purpose of the Study:

• To compare amino acid sequences of m5C DNA methyltransferases (Mtases) from diverse prokaryotic and eukaryotic species.
• To investigate the conserved and variable regions within these enzymes, particularly the target-recognizing domains (TRDs).
• To identify potential TRDs in monospecific Mtases based on sequence similarities.

Main Methods:

• Comparative analysis of amino acid sequences of m5C DNA methyltransferases from 11 prokaryotes and 1 eukaryote.
• Identification and comparison of conserved "core" sequences and "variable" regions.
• Detailed examination of amino acid sequences within the target-recognizing domains (TRDs) of phage Mtases.

Main Results:

• A highly similar organization was observed in m5C DNA methyltransferases across the studied species.
• Conserved "core" sequences likely mediate common methylation reaction steps, while variable regions contain TRDs.
• Analysis of phage Mtase TRDs revealed both conserved and variable amino acids, leading to a proposed "consensus" TRD sequence.

Conclusions:

• The conserved amino acids in TRDs form a consensus sequence defining the domain.
• Variable residues within the TRDs determine enzyme specificity.
• Identified consensus sequences show similarity to regions in monospecific Mtases, predicting their role as part of TRDs.