Seres Therapeutics has leased 83,000 square feet in Cambridge and will relocate its headquarters in three phases beginning in early 2016.

The lease brings BioMed Realty’s 200 Sidney St. property to 100 percent occupancy and allows Seres to bring its research, manufacturing, corporate and commercial units together under the same roof. Seres becomes the largest tenant of the building, which also includes AbbVie, CRISPR Therapeutics, RaNA Therapeutics and Synlogic.

Seres is expanding after completing a $140 million IPO. The company develops bacteria-based treatments for gastrointestinal ailments.

The phased move begins next spring beginning with office and lab functions. The leases run through November 2023.

The property contains 338,000 square feet of office and lab space in three buildings, part of the former Vertex Pharmaceuticals complex that is being repositioned by BioMed in the wake of Vertex’s move to Boston’s Seaport District and termination of its Sidney Street lease in early 2015.

Transwestern | RBJ represented BioMed and Newmark Grubb Knight Frank represented Seres in the transaction.