Switzerland-based Roche Holdings AG has begun the reshuffling process of several of its executives following its $46.8 billion takeover of biotechnology company Genentech in March.

Among the moves, Genentech’s current Chairman and CEO Arthur Levinson will chair Roche’s new board of directors. Meanwhile, Roche CEO William Burns will retire from the corporate executive committee on Jan. 1, 2010. The board has not yet announced a successor.

In addition, Roche will appoint Pascal Soriot chief executive of Genentech North America, which combines the commercial operations of Rocha Pharma North America and Genentech. There, Soriot also will serve as a member of the corporate executive committee.

In related news, Genentech CFO David Ebersman and Chief Compliance Officer Steve Juelsgaard will leave the company.

The organizational changes become effective May 1.