Well to begin with it might be good to change your perspective of the project manager's role from "over" to "with"—otherwise you could be in for a long cold winter with a forecast of frosty relationships. Keep in mind that all team members are contributing equally to the same goal, but that they each are bringing different skills and capabilities to the project. With this perspective, you need to promote your role as project manager as a facilitator
to help the team work toward success, an obstacle remover
who is there to make their lives easier. The ringmaster at a circus is a minor contributor of the core entertainment, but has a critical role to the outcome none-the-less—what the ringmaster does throughout the show is critical to setting the tone, setting the stage, and coordinating the various acts to work seamlessly together. The project manager leads, coordinates, facilitates, and removes obstacles—all of which should help, not threaten, any peers who are now part of your project team.
Our Team Roles and Responsibilities List is an excellent tool to facilitate the dialogue across your project team, allowing each member to define their role and responsibility to the project, including you, and resolve any concerns or misconceptions right up front. See also our paper "Getting Relevant to Get Results: How to be a project manager that team members love." It discusses how to not be perceived as ineffective overhead with undue authority over those doing the work, but rather a partner in getting the work done, with lots of value to bring through the PM role.