Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, CA, USA.|Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, CA, USA.|Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, CA, USA.|Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, CA, USA.