Moving from E to J [at MIA]
 

I am arriving from nassau into Miami on American concourse E and need to get to J for Virgin Atlantic flight.

If already cleared customs in nassau and bag checked through to London is 2 hour and 15 minutes sufficient connection time?

Yes, plenty of time. Even if you have to claim and recheck your bag at MIA (which might be a good idea to improve the chances of it not getting lost), you'll be fine.