Interleaved dimers and higher order symmetric oligomers are ubiquitous in biology but present a challenge to de novo structure prediction methodology: The structure adopted by a monomer can be stabilized largely by interactions with other monomers and hence not the lowest energy state of a single chain. Building on the Rosetta framework, we present a general method to simultaneously model the folding and docking of multiple-chain interleaved homo-oligomers. For more than a third of the cases in a benchmark set of interleaved homo-oligomers, the method generates near-native models of large ␣-helical bundles, interlocking  sandwiches, and interleaved ␣/ motifs with an accuracy high enough for molecular replacement based phasing. With the incorporation of NMR chemical shift information, accurate models can be obtained consistently for symmetric complexes with as many as 192 total amino acids; a blind prediction was within 1 Å rmsd of the traditionally determined NMR structure, and fit independently collected RDC data equally well. Together, these results show that the Rosetta ''fold-and-dock'' protocol can produce models of homo-oligomeric complexes with nearatomic-level accuracy and should be useful for crystallographic phasing and the rapid determination of the structures of multimers with limited NMR information.homo-oligomers ͉ molecular replacement ͉ NMR structure inference ͉ protein structure prediction ͉ symmetry T he majority of expressed proteins function within symmetrical homomeric complexes (1-3). Although a boon for evolving functional diversity (4), this ubiquity of oligomeric structures poses numerous challenges for modern structural biology. The phasing of crystallographic data by molecular replacement and NMR structural inference are complicated by the increasing number of degrees of freedom and spectral degeneracy, respectively, in multimeric systems. The ability to predict de novo the structures of multiple interacting molecular chains would potentially alleviate these problems, allowing unphased diffraction measurements or ambiguously assigned NMR spectra to be resurrected as constraints or as independent validation for in silico structural inference.Accurate modeling of previously unseen homomeric structures has not been demonstrated at high resolution. Significant progress has occurred in modeling the folds of individual monomeric soluble proteins (5-7) and the docking arrangements of predefined monomers (8, 9). However, as proteins interact with other proteins, nucleic acids, or smaller molecules, their lowest free-energy backbone conformations typically shift in response to their partners. These often dramatic structural changes have been a persistent and unsolved issue in blind prediction trials of recent years (8).In this report, we show how two different methods developed for de novo conformational sampling (for folding and for docking) can be melded into a more general procedure that permits the blind prediction of intertwined complexes of proteins at near-atomic resolution. Some of th...