Why treat plasmid DNA with alkaline phosphatase when making a recombinant plasmid?
 

When attempting to create a recombinant DNA molecule, by inserting a foreign sequence into the vector plasmid; what is the point (and how does it achieve it) of treating the plasmid DNA with alkaline phosphatase?

I think it has something to do with the orientation of the inserted sequence, but unsure how the treatment achieves this.

Re: Why treat plasmid DNA with alkaline phosphatase when making a recombinant plasmid
 

Here is my understanding of phosphatases:

Vectors are normally treated with alkaline phosphatases, such as CIP, following a digestion in order to prevent re-ligation of the vector in the absence of the insert. The phosphatase removes the 5' phosphate group so that it cannot interact with the 3' hydroxyl group. Thus, when a ligation is performed you increase your likelihood that your vector contains your insert and not just an empty vector.

I hope it helps!

Re: Why treat plasmid DNA with alkaline phosphatase when making a recombinant plasmid
 

phosphatase is used to remove phosphate group from the 5'end to prevent self ligation.