The prokaryotic origin of the pathways for synthesis and post-synthetic modification of deoxyribonucleic acid

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Methionine serves as a crucial methyl group donor in DNA synthesis and modification pathways in mammals.
• Bacterial DNA modification involves enzymes forming N6-methyladenine (m6A) and 5-methylcytosine (m5C).

Purpose of the Study:

• To investigate the origin and regulation of DNA methylation pathways in bacteria.
• To analyze the formation rates of m6A and m5C during the bacterial cell cycle.
• To determine if bacterial DNA methyltransferase activities are coordinated.

Main Methods:

• Bacterial culture and cell cycle synchronization.
• Enzymatic assays to measure DNA methyltransferase activity.
• Analysis of DNA methylation patterns (m6A and m5C) at different cell cycle stages.

Main Results:

• Bacterial DNA methylation pathways, similar to mammals, utilize methionine.
• Enzymatic systems in bacteria form both m6A and m5C on DNA.
• The formation rate of m6A decreased throughout the bacterial cell cycle (CGC).
• The formation rate of m5C peaked in the middle of the bacterial CGC.
• Differential kinetics of m6A and m5C formation were observed.

Conclusions:

• Bacterial DNA methylation pathways originate from conserved mechanisms involving methionine.
• The observed shift in formation rates suggests that dam and dcm methyltransferase activities, and potentially RM enzyme moieties, are uncoupled during the bacterial cell cycle.