The departure of anchor tenant WeWork is providing the impetus for the latest proposed office-to-lab conversion in downtown Boston.

Oxford Properties Group is seeking to convert 155,000 square feet at its 745 Atlantic Ave. property into life science and R&D-ready space, after being notified of the anchor tenant’s intent to default on its lease and leave 75 percent of the building vacant.

The project will include updates to the building’s utility systems and infrastructure to support lab use, according to a notification letter submitted to the Boston Planning & Development Agency by Mark McGowan, a vice president at Oxford.

“We believe this approach, which provides Oxford the flexibility to accommodate a variety of tenants according to future demand, will limit the duration and impacts of the vacancy and position the building for success in Boston’s rapidly evolving knowledge economy,” McGowan wrote.

The project also would include an updated lobby and 4,100 square feet for a new full-service restaurant replacing a former conference space.

The Canadian real estate investor bought the 11-story, 174,000-square-foot office complex across from South Station in 2015 for $114.5 million.

Oxford is pursuing a life science strategy at a second property in the Leather District, where it’s proposing a 393,500-square-foot office and lab tower at 125 Lincoln St., after originally seeking approval for a taller office tower.