[Bidagdha_TADIR]

I was studying gene cloning and I came across this - cosmids after recombination will form concatemers and then be packaged into virus capsids.

So what I understand is - a cosmid is cut be restriction enzyme to produce a linear DNA. Then the passenger DNA is placed and DNA ligase is used to produce rDNA. A concatemer is formed and a capsid will take up sequence between two cos sites of the concatemer. then the concatemer will move to next capsid and so on.

So why plasmid doesn't form the linear concatemer instead of circular rDNA. AS far as I can see, the cos site is intact in the cosmid when it is cut with RE. So presence or absence of cos site doesn't affect formation of concatemer. cos site only affect packaging of rDNA into capsid.