The Proceedings of the National Academy of Sciences has unusual submission procedures. Most submissions go through Direct Review, which is similar to the traditional review process at most scholarly journals, except that "Authors must recommend three appropriate Editorial Board members, three NAS members who are expert in the paper's scientific area, and five qualified reviewers." Alternatively, authors may ask any elected member of the National Academy of Sciences to serve as a Prearranged Editor (PE), who will then lead the review process. Although the procedures say that "PEs should be used only when an article falls into an area without broad representation in the Academy, or for research that may be considered counter to a prevailing view or too far ahead of its time to receive a fair hearing, and in which the member is expert." defining these boundaries is difficult.
Although I respect the role of journal editor and deeply appreciate and honor those who take on this crucial job in our profession, I prefer to make my contributions in other ways. So I normally decline invitations to serve as PE (or member-editor, which is another category) for PNAS (and as editor, associate editor, etc., for other journals). If you think I'd be appropriate, I'd be more than happy to serve as reviewer, as I do write numerous reviews. In addition, I have an arrangement with members of the PNAS editorial board in subfields I touch on where I take on some aspects of the editorial role by recommending scholars to serve as reviewers and editors and so, although I'd rather not be a PE, I might be able to help some anyway.
And regardless, best of luck with your paper!
(p.s. Yes, it is true that I served as founding editor of The Political Methodologist, but it was the "founding" part of "founding editor" that I enjoyed!)