Backlog assignments across domains & teams

[Brent Heckerman]

Four agile teams, one product backlog. The teams have been mostly formed based on location, but also according to some functional area of focus. So West Coast team might be working mostly on domains A and B. East Coast domains C and D, etc.

Ideally teams would select work items from the backlog that match their domain and start working the assignment.

However it may be that the East Coast team is able to tackle something in Domain A.
So what might be a good way to manage this in a tool like JIRA?

They could use an assignment value on the JIRA item and show all four teams, and when a team takes an assignment they just remove the other three teams. 

Is there a better way to handle this?