Beta class amino methyltransferases from bacteria to humans: evolution and structural consequences.

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• S-adenosyl-l-methionine dependent methyltransferases are crucial enzymes catalyzing methyl transfers.
• A specific family, class beta methyltransferases (MTases), targets adenine or cytosine amino groups in DNA.
• Members include M.EcoGII, M.EcoP15I, CcrM, MTA1-MTA9, and MettL3-MettL14 complexes.

Purpose of the Study:

• To discuss the conserved features and functions of class beta methyltransferases.
• To highlight the unique dimeric structure and substrate specificity of these enzymes.
• To propose M.EcoGII as a potential ancestral methyltransferase.

Main Methods:

• Comparative analysis of amino acid sequences to identify conserved motifs.
• Review of existing literature on the enzymatic activity and substrate specificity of class beta MTases.
• Functional characterization of M.EcoGII in relation to other class beta members.

Main Results:

• Class beta MTases share conserved motifs and primarily generate N6-methyladenine in DNA.
• Some members exhibit activity on single-stranded DNA and RNA.
• These enzymes form homo- or hetero-dimers, enabling specialized functions.
• M.EcoGII displays broad substrate independence (nucleic acid type, strandedness, sequence).

Conclusions:

• Class beta methyltransferases represent a functionally diverse group with a conserved structural basis.
• The dimeric nature facilitates substrate recognition and methylation efficiency.
• M.EcoGII's broad activity suggests it may be an ancestral enzyme in this class.