The latest step in Rupert Murdoch’s effort to turn around the fortunes of his digital businesses came Tuesday in the form of hefty layoffs at MySpace.

MySpace, the social networking site owned by News Corporation, the media conglomerate controlled by Mr. Murdoch, said it was laying off roughly 400 employees, or nearly 30 percent of its staff. After the layoffs, MySpace will have about 1,000 workers.

The company said the layoffs were an attempt to return to a “start-up culture.”

In a statement, Owen Van Natta, a former Facebook executive who became chief executive of MySpace in April, said: “Simply put, our staffing levels were bloated and hindered our ability to be an efficient and nimble team-oriented company. I understand these changes are painful for many. They are also necessary for the long-term health and culture of MySpace. Our intent is to return to an environment of innovation that is centered on our user and our product.”

MySpace, which was acquired by News Corporation in 2005 for $580 million, was once the pre-eminent social networking site. But more recently it has lost some luster to Facebook, and at the same time has come up short of News Corporation’s financial projections.