Question

What is the role of methylase in E. coli?
(correct answer + 1, wrong answer - 0.25)

• A. Protection of host DNA from the action of restriction endonuclease
• B. Ligation of the two cohesive ends of DNA molecule.
• C. Removal of the methyl group
• D. Cutting of the DNA of bacteriophage at specific sites.

Answer 1

The correct option is A Protection of host DNA from the action of restriction endonuclease

Methylase enzyme in E. coli protects the bacterial DNA from the action of restriction endonucleases by adding methyl groups to one or two bases within the sequence recognized by restriction enzyme. Methylation prevents the action of restriction endonuclease as it is no longer able to identify the active site for binding.