title: Drosophila Nanos acts as a molecular clamp that modulates the RNA-binding and repression activities of Pumilio.
abstract: Collaboration among the multitude of RNA-binding proteins (RBPs) is ubiquitous, yet our understanding of these key regulatory complexes has been limited to single RBPs. We investigated combinatorial translational regulation by Drosophila Pumilio (Pum) and Nanos (Nos), which control development, fertility, and neuronal functions. Our results show how the specificity of one RBP (Pum) is modulated by cooperative RNA recognition with a second RBP (Nos) to synergistically repress mRNAs. Crystal structures of Nos-Pum-RNA complexes reveal that Nos embraces Pum and RNA, contributes sequence-specific contacts, and increases Pum RNA-binding affinity. Nos shifts the recognition sequence and promotes repression complex formation on mRNAs that are not stably bound by Pum alone, explaining the preponderance of sub-optimal Pum sites regulated in vivo. Our results illuminate the molecular mechanism of a regulatory switch controlling crucial gene expression programs, and provide a framework for understanding how the partnering of RBPs evokes changes in binding specificity that underlie regulatory network dynamics.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, United States.
authors.forename: Chase A
authors.initials: CA
authors.lastname: Weidmann
authors.affiliation: Epigenetics and Stem Cell Biology Laboratory, National Institutes of Health, Research Triangle Park, United States.|National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, United States.
authors.forename: Chen
authors.initials: C
authors.lastname: Qiu
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, United States.
authors.forename: René M
authors.initials: RM
authors.lastname: Arvola
authors.affiliation: Department of Biological Sciences, University of Texas at Dallas, Richardson, United States.
authors.forename: Tzu-Fang
authors.initials: TF
authors.lastname: Lou
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, United States.
authors.forename: Jordan
authors.initials: J
authors.lastname: Killingsworth
authors.affiliation: Department of Biological Sciences, University of Texas at Dallas, Richardson, United States.
authors.forename: Zachary T
authors.initials: ZT
authors.lastname: Campbell
authors.affiliation: Epigenetics and Stem Cell Biology Laboratory, National Institutes of Health, Research Triangle Park, United States.|National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, United States.
authors.forename: Traci M
authors.initials: TM
authors.lastname: Tanaka Hall
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, United States.|Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States.
authors.forename: Aaron C
authors.identifier: 0000-0002-1867-8763
authors.initials: AC
authors.lastname: Goldstrohm
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism*; D005786:Gene Expression Regulation; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C074333:pum protein, Drosophila; C070574:nos protein, Drosophila; D012313:RNA
keywords: D. melanogaster; Nanos; Pumilio; biophysics; cooperative RNA-binding; developmental biology; stem cells; structural biology; translational repression