Mr. Gatti's LP, the Austin-based pizza chain, said it will undertake the biggest expansion in its history by adding 22 locations in Tennessee over the next seven years. The company has signed a development agreement with Pizza Southeast, a Knoxville-based franchise group. The franchise group also has purchased three corporate-owned Mr. Gatti's in the Knoxville area. Jim Eure, a retired Air Force officer, started Mr. Gatti's in 1969 and sold the chain, then with 18 restaurants, in 1974. It changed hands several times. Blue Sage Capital LP bought the 150-store chain in 2004 for $23.6 million. It ranks among the top 25 pizza chains by sales, according to Pizza Market Quarterly.