DNA Linkers

What is a Linker?

The linkers are short double-stranded sequences of DNA. They have blunt ends. They are chemically synthesized oligonucleotides. They are ligated with the blunt ends of a vector of foreign DNA.

It contains restriction sites for the identification of restriction enzymes. The restriction enzymes cleave the ligated linker and the DNA fragment to produce cohesive or sticky ends.

One drawback of linkers is that the foreign DNA fragment sometimes already possesses restriction sites for the enzymes that are used to cut the linker, resulting in cleaving the DNA internally. This limits the use of linker molecules.

Example: Eco-RI linkers and Sal-I linkers

Short sequences of ds-Oligonucleotides.

Chemically Synthesized.

Possess one or more Restriction Endonuclease sites within them.

Linkers are joined to Blunt end DNA Fragments followed by cleavage with Restriction endonuclease results in the conversion of Blunt of DNA segment to Sticky ended fragments.

Applications

Creation of cohesive ends.

Used for the fragments having unmatched or undefined sequences in the protruding end.

Disadvantage

There can be restriction site in the linker itself and enzyme used can cut the DNA fragment into multiple segments.