Neisseria gonorrhoeae M.Ngo AI DNA methyltransferase: physical and catalytic properties of the homogeneous enzyme

Area of Science:

• Biochemistry
• Molecular Biology
• Microbiology

Background:

• DNA methyltransferases play vital roles in DNA replication, repair, and gene regulation.
• Neisseria gonorrhoeae possesses various enzymes for DNA modification.

Purpose of the Study:

• To purify and characterize the DNA methyltransferase M.NgoAI from Neisseria gonorrhoeae strain WR220.
• To determine the enzyme's molecular weight, optimal activity conditions, and kinetic parameters.

Main Methods:

• Purification using successive column chromatography.
• Molecular weight determination via gel filtration and denaturing polyacrylamide gel electrophoresis.
• Enzymatic activity assays to determine optimal conditions and kinetic parameters (Km).

Main Results:

• M.NgoAI was purified to homogeneity with a molecular weight of 25,000 Da.
• Maximal enzymatic activity was observed at 37°C in 50 mM Tris.HCl (pH 7.4) with 10 mM EDTA.
• Apparent Km values for S-adenosylmethionine and 5'-GGCC sites were 1.25 µM and 89.6 nM, respectively.

Conclusions:

• The DNA methyltransferase M.NgoAI from N. gonorrhoeae has been successfully purified and characterized.
• The determined kinetic parameters provide insights into the enzyme's substrate specificity and catalytic efficiency.