Project Summary / Abstract The Center engages in collaborative research that leverages the Center's molecular modeling software, expertise and facilities to bridge experiment and computation. While experimental techniques unveil critical aspects of molecular and cellular architecture, computational molecular modeling describes biomolecular systems in their native states at the atomic level. During the last funding period, the Center completed 35 Collaboration and Service projects with 41 joint publications on subjects such as the assembly mechanism and drug resistance of the ribosome, neurons' synaptic receptors and solid-state DNA sequencing nanopores. Currently, the Center is engaged in 42 ongoing collaboration projects with 56 joint publications so far. To make the Center's technological advances driven by the collaboration projects available to the biomedical community, the Center distributes its software for all major platforms, from laptops to supercomputers and cloud computing facilities. The Center ensures software usability by providing user support, maintaining up-to-date documentation, tutorials, and online discussion groups. Over the last funding period, the Center-developed molecular modeling and simulation packages VMD, NAMD, and Lattice Microbes served a community of over 100,000 users. Technical support for the community was provided mainly through the online discussion groups “NAMD-L”, “VMD-L” and “LatticeMicrobes-Users”, where more than 17,000 software-related messages were submitted over the last funding periode. The Center also offers individual consultation for special cases requiring direct personal interaction, operating directly in its laboratory area a well-equipped Visitor Center to host visiting scholars and collaborators. 50 scholars/collaborators visited the Center for up to six months seeking technical and scientific expertise, and 107 leading scientists presented their work on the Center Seminar program at the host institution, the UIUC Beckman Institute. All the activities described above were possible only through the Center's Petascale Biology Gateway Facility, which provides the high-end computing and graphics resources required by the demanding preparation, visualization, and analysis tasks of advanced molecular modeling. This gateway also hosts the Center's website and all associated content, from scientific research-related material to software documentation and tutorials, as well as the online discussion platforms.