title: Polyribosomes are molecular 3D nanoprinters that orchestrate the assembly of vault particles.
abstract: Ribosomes are molecular machines that function in polyribosome complexes to translate genetic information, guide the synthesis of polypeptides, and modulate the folding of nascent proteins. Here, we report a surprising function for polyribosomes as a result of a systematic examination of the assembly of a large ribonucleoprotein complex, the vault particle. Structural and functional evidence points to a model of vault assembly whereby the polyribosome acts like a 3D nanoprinter to direct the ordered translation and assembly of the multi-subunit vault homopolymer, a process which we refer to as polyribosome templating. Structure-based mutagenesis and cell-free in vitro expression studies further demonstrated the critical importance of the polyribosome in vault assembly. Polyribosome templating prevents chaos by ensuring efficiency and order in the production of large homopolymeric protein structures in the crowded cellular environment and might explain the origin of many polyribosome-associated molecular assemblies inside the cell.
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine, ‡Department of Microbiology, Immunology & Molecular Genetics, and §California Nanosystems Institute, University of California at Los Angeles , Los Angeles, California 90095, United States.
authors.forename: Jan
authors.initials: J
authors.lastname: Mrazek
authors.forename: Daniel
authors.initials: D
authors.lastname: Toso
authors.forename: Sergey
authors.initials: S
authors.lastname: Ryazantsev
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.forename: Z Hong
authors.initials: ZH
authors.lastname: Zhou
authors.forename: Beatriz Campo
authors.initials: BC
authors.lastname: Fernandez
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Kickhoefer
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Rome
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D008969:Molecular Sequence Data; D011132:Polyribosomes; D066330:Printing, Three-Dimensional; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D014057:Tomography, X-Ray Computed
keywords: cryo-electron tomography; nanoprinting; polyribosome function; structure-based mutagenesis; vault particle