* Now sees synergies of 400-500 mln eur
(Adds details on deal, labour comments):
FRANKFURT/DUESSELDORF (Reuters) - Thyssenkrupp’s (TKAG.DE) supervisory board on Friday gave the green light for a steel joint venture with Tata Steel (TISC.NS), paving the way for the European steel sector’s biggest shake-up in more than a decade. The largest deal in Europe’s steel industry since the takeover of Arcelor by Mittal in 2006, the 50-50 joint venture - to be named Thyssenkrupp Tata Steel - will have about 48,000 workers and about 15 billion euros ($17.5 billion) in sales.