@article{18778, abstract = {Transcription by RNA polymerase II (Pol II) can be repressed by noncoding RNA, including the human RNA Alu. However, the mechanism by which endogenous RNAs repress transcription remains unclear. Here we present cryogenic-electron microscopy structures of Pol II bound to Alu RNA, which reveal that Alu RNA mimics how DNA and RNA bind to Pol II during transcription elongation. Further, we show how distinct domains of the general transcription factor TFIIF control repressive activity. Together, we reveal how a noncoding RNA can regulate mammalian gene expression.}, author = {Tluckova, Katarina and Kaczmarek, Beata M and Testa Salmazo, Anita P and Bernecky, Carrie A}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, pages = {607--612}, publisher = {Springer Nature}, title = {{Mechanism of mammalian transcriptional repression by noncoding RNA}}, doi = {10.1038/s41594-024-01448-7}, volume = {32}, year = {2025}, } @article{17884, abstract = {Human T cell leukemia virus type 1 (HTLV-1) immature particles differ in morphology from other retroviruses, suggesting a distinct way of assembly. Here we report the results of cryo-electron tomography studies of HTLV-1 virus-like particles assembled in vitro, as well as derived from cells. This work shows that HTLV-1 uses a distinct mechanism of Gag–Gag interactions to form the immature viral lattice. Analysis of high-resolution structural information from immature capsid (CA) tubular arrays reveals that the primary stabilizing component in HTLV-1 is the N-terminal domain of CA. Mutagenesis analysis supports this observation. This distinguishes HTLV-1 from other retroviruses, in which the stabilization is provided primarily by the C-terminal domain of CA. These results provide structural details of the quaternary arrangement of Gag for an immature deltaretrovirus and this helps explain why HTLV-1 particles are morphologically distinct.}, author = {Obr, Martin and Percipalle, Mathias and Chernikova, Darya and Yang, Huixin and Thader, Andreas and Pinke, Gergely and Porley, Dario J and Mansky, Louis M. and Dick, Robert A. and Schur, Florian KM}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, pages = {268--276}, publisher = {Springer Nature}, title = {{Distinct stabilization of the human T cell leukemia virus type 1 immature Gag lattice}}, doi = {10.1038/s41594-024-01390-8}, volume = {32}, year = {2025}, } @article{14979, abstract = {Poxviruses are among the largest double-stranded DNA viruses, with members such as variola virus, monkeypox virus and the vaccination strain vaccinia virus (VACV). Knowledge about the structural proteins that form the viral core has remained sparse. While major core proteins have been annotated via indirect experimental evidence, their structures have remained elusive and they could not be assigned to individual core features. Hence, which proteins constitute which layers of the core, such as the palisade layer and the inner core wall, has remained enigmatic. Here we show, using a multi-modal cryo-electron microscopy (cryo-EM) approach in combination with AlphaFold molecular modeling, that trimers formed by the cleavage product of VACV protein A10 are the key component of the palisade layer. This allows us to place previously obtained descriptions of protein interactions within the core wall into perspective and to provide a detailed model of poxvirus core architecture. Importantly, we show that interactions within A10 trimers are likely generalizable over members of orthopox- and parapoxviruses.}, author = {Datler, Julia and Hansen, Jesse and Thader, Andreas and Schlögl, Alois and Bauer, Lukas W and Hodirnau, Victor-Valentin and Schur, Florian KM}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, pages = {1114--1123}, publisher = {Springer Nature}, title = {{Multi-modal cryo-EM reveals trimers of protein A10 to form the palisade layer in poxvirus cores}}, doi = {10.1038/s41594-023-01201-6}, volume = {31}, year = {2024}, } @article{18645, abstract = {Gene expression during natural and induced reprogramming is controlled by pioneer transcription factors that initiate transcription from closed chromatin. Nr5a2 is a key pioneer factor that regulates zygotic genome activation in totipotent embryos, pluripotency in embryonic stem cells and metabolism in adult tissues, but the mechanism of its pioneer activity remains poorly understood. Here, we present a cryo-electron microscopy structure of human NR5A2 bound to a nucleosome. The structure shows that the conserved carboxy-terminal extension (CTE) loop of the NR5A2 DNA-binding domain competes with a DNA minor groove anchor of the nucleosome and releases entry-exit site DNA. Mutational analysis showed that NR5A2 D159 of the CTE is dispensable for DNA binding but required for stable nucleosome association and persistent DNA ‘unwrapping’. These findings suggest that NR5A2 belongs to an emerging class of pioneer factors that can use DNA minor groove anchor competition to destabilize nucleosomes and facilitate gene expression during reprogramming.}, author = {Kobayashi, Wataru and Sappler, Anna H. and Bollschweiler, Daniel and Kümmecke, Maximilian and Basquin, Jérôme and Arslantas, Eda Nur and Ruangroengkulrith, Siwat and Hornberger, Renate and Duderstadt, Karl and Tachibana, Kikuë}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, pages = {757--766}, publisher = {Springer Nature}, title = {{Nucleosome-bound NR5A2 structure reveals pioneer factor mechanism by DNA minor groove anchor competition}}, doi = {10.1038/s41594-024-01239-0}, volume = {31}, year = {2024}, } @article{15323, abstract = {Supercomplexes of the respiratory chain are established constituents of the oxidative phosphorylation system, but their role in mammalian metabolism has been hotly debated. Although recent studies have shown that different tissues/organs are equipped with specific sets of supercomplexes, depending on their metabolic needs, the notion that supercomplexes have a role in the regulation of metabolism has been challenged. However, irrespective of the mechanistic conclusions, the composition of various high molecular weight supercomplexes remains uncertain. Here, using cryogenic electron microscopy, we demonstrate that mammalian (mouse) tissues contain three defined types of ‘respirasome’, supercomplexes made of CI, CIII2 and CIV. The stoichiometry and position of CIV differs in the three respirasomes, of which only one contains the supercomplex-associated factor SCAF1, whose involvement in respirasome formation has long been contended. Our structures confirm that the ‘canonical’ respirasome (the C-respirasome, CICIII2CIV) does not contain SCAF1, which is instead associated to a different respirasome (the CS-respirasome), containing a second copy of CIV. We also identify an alternative respirasome (A-respirasome), with CIV bound to the ‘back’ of CI, instead of the ‘toe’. This structural characterization of mouse mitochondrial supercomplexes allows us to hypothesize a mechanistic basis for their specific role in different metabolic conditions.}, author = {Vercellino, Irene and Sazanov, Leonid A}, issn = {1545-9985}, journal = {Nature Structural and Molecular Biology}, pages = {1061--1071}, publisher = {Springer Nature}, title = {{SCAF1 drives the compositional diversity of mammalian respirasomes}}, doi = {10.1038/s41594-024-01255-0}, volume = {31}, year = {2024}, } @article{15149, abstract = {The genomic binding sites of the transcription factor (TF) and tumor suppressor p53 are unusually diverse with regard to their chromatin features, including histone modifications, raising the possibility that the local chromatin environment can contextualize p53 regulation. Here, we show that epigenetic characteristics of closed chromatin, such as DNA methylation, do not influence the binding of p53 across the genome. Instead, the ability of p53 to open chromatin and activate its target genes is locally restricted by its cofactor Trim24. Trim24 binds to both p53 and unmethylated histone 3 lysine 4 (H3K4), thereby preferentially localizing to those p53 sites that reside in closed chromatin, whereas it is deterred from accessible chromatin by H3K4 methylation. The presence of Trim24 increases cell viability upon stress and enables p53 to affect gene expression as a function of the local chromatin state. These findings link H3K4 methylation to p53 function and illustrate how specificity in chromatin can be achieved, not by TF-intrinsic sensitivity to histone modifications, but by employing chromatin-sensitive cofactors that locally modulate TF function.}, author = {Isbel, Luke and Iskar, Murat and Durdu, Sevi and Weiss, Joscha and Grand, Ralph S. and Hietter-Pfeiffer, Eric and Kozicka, Zuzanna and Michael, Alicia and Burger, Lukas and Thomä, Nicolas H. and Schübeler, Dirk}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, number = {7}, pages = {948--957}, publisher = {Springer Nature}, title = {{Readout of histone methylation by Trim24 locally restricts chromatin opening by p53}}, doi = {10.1038/s41594-023-01021-8}, volume = {30}, year = {2023}, } @article{12262, abstract = {The AAA-ATPase Drg1 is a key factor in eukaryotic ribosome biogenesis that initiates cytoplasmic maturation of the large ribosomal subunit. Drg1 releases the shuttling maturation factor Rlp24 from pre-60S particles shortly after nuclear export, a strict requirement for downstream maturation. The molecular mechanism of release remained elusive. Here, we report a series of cryo-EM structures that captured the extraction of Rlp24 from pre-60S particles by Saccharomyces cerevisiae Drg1. These structures reveal that Arx1 and the eukaryote-specific rRNA expansion segment ES27 form a joint docking platform that positions Drg1 for efficient extraction of Rlp24 from the pre-ribosome. The tips of the Drg1 N domains thereby guide the Rlp24 C terminus into the central pore of the Drg1 hexamer, enabling extraction by a hand-over-hand translocation mechanism. Our results uncover substrate recognition and processing by Drg1 step by step and provide a comprehensive mechanistic picture of the conserved modus operandi of AAA-ATPases.}, author = {Prattes, Michael and Grishkovskaya, Irina and Hodirnau, Victor-Valentin and Hetzmannseder, Christina and Zisser, Gertrude and Sailer, Carolin and Kargas, Vasileios and Loibl, Mathias and Gerhalter, Magdalena and Kofler, Lisa and Warren, Alan J. and Stengel, Florian and Haselbach, David and Bergler, Helmut}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, number = {9}, pages = {942--953}, publisher = {Springer Nature}, title = {{Visualizing maturation factor extraction from the nascent ribosome by the AAA-ATPase Drg1}}, doi = {10.1038/s41594-022-00832-5}, volume = {29}, year = {2022}, } @article{15131, abstract = {RNA modifications are widespread in biology and abundant in ribosomal RNA. However, the importance of these modifications is not well understood. We show that methylation of a single nucleotide, in the catalytic center of the large subunit, gates ribosome assembly. Massively parallel mutational scanning of the essential nuclear GTPase Nog2 identified important interactions with rRNA, particularly with the 2′-O-methylated A-site base Gm2922. We found that methylation of G2922 is needed for assembly and efficient nuclear export of the large subunit. Critically, we identified single amino acid changes in Nog2 that completely bypass dependence on G2922 methylation and used cryoelectron microscopy to directly visualize how methylation flips Gm2922 into the active site channel of Nog2. This work demonstrates that a single RNA modification is a critical checkpoint in ribosome biogenesis, suggesting that such modifications can play an important role in regulation and assembly of macromolecular machines.}, author = {Yelland, James N. and Bravo, Jack Peter Kelly and Black, Joshua J. and Taylor, David W. and Johnson, Arlen W.}, issn = {1545-9985}, journal = {Nature Structural & Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, pages = {91--98}, publisher = {Springer Nature}, title = {{A single 2′-O-methylation of ribosomal RNA gates assembly of a functional ribosome}}, doi = {10.1038/s41594-022-00891-8}, volume = {30}, year = {2022}, } @article{8581, abstract = {The majority of adenosine triphosphate (ATP) powering cellular processes in eukaryotes is produced by the mitochondrial F1Fo ATP synthase. Here, we present the atomic models of the membrane Fo domain and the entire mammalian (ovine) F1Fo, determined by cryo-electron microscopy. Subunits in the membrane domain are arranged in the ‘proton translocation cluster’ attached to the c-ring and a more distant ‘hook apparatus’ holding subunit e. Unexpectedly, this subunit is anchored to a lipid ‘plug’ capping the c-ring. We present a detailed proton translocation pathway in mammalian Fo and key inter-monomer contacts in F1Fo multimers. Cryo-EM maps of F1Fo exposed to calcium reveal a retracted subunit e and a disassembled c-ring, suggesting permeability transition pore opening. We propose a model for the permeability transition pore opening, whereby subunit e pulls the lipid plug out of the c-ring. Our structure will allow the design of drugs for many emerging applications in medicine.}, author = {Pinke, Gergely and Zhou, Long and Sazanov, Leonid A}, issn = {1545-9985}, journal = {Nature Structural and Molecular Biology}, number = {11}, pages = {1077--1085}, publisher = {Springer Nature}, title = {{Cryo-EM structure of the entire mammalian F-type ATP synthase}}, doi = {10.1038/s41594-020-0503-8}, volume = {27}, year = {2020}, } @article{8438, author = {Kurauskas, Vilius and Hessel, Audrey and Dehez, François and Chipot, Christophe and Bersch, Beate and Schanda, Paul}, issn = {1545-9993}, journal = {Nature Structural & Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, number = {9}, pages = {745--747}, publisher = {Springer Nature}, title = {{Dynamics and interactions of AAC3 in DPC are not functionally relevant}}, doi = {10.1038/s41594-018-0127-4}, volume = {25}, year = {2018}, } @article{515, abstract = {The oxidative phosphorylation electron transport chain (OXPHOS-ETC) of the inner mitochondrial membrane is composed of five large protein complexes, named CI-CV. These complexes convert energy from the food we eat into ATP, a small molecule used to power a multitude of essential reactions throughout the cell. OXPHOS-ETC complexes are organized into supercomplexes (SCs) of defined stoichiometry: CI forms a supercomplex with CIII2 and CIV (SC I+III2+IV, known as the respirasome), as well as with CIII2 alone (SC I+III2). CIII2 forms a supercomplex with CIV (SC III2+IV) and CV forms dimers (CV2). Recent cryo-EM studies have revealed the structures of SC I+III2+IV and SC I+III2. Furthermore, recent work has shed light on the assembly and function of the SCs. Here we review and compare these recent studies and discuss how they have advanced our understanding of mitochondrial electron transport.}, author = {Letts, James A and Sazanov, Leonid A}, issn = {1545-9993}, journal = {Nature Structural and Molecular Biology}, number = {10}, pages = {800 -- 808}, publisher = {Nature Publishing Group}, title = {{Clarifying the supercomplex: The higher-order organization of the mitochondrial electron transport chain}}, doi = {10.1038/nsmb.3460}, volume = {24}, year = {2017}, } @article{3141, abstract = {The two actin-related subunits of the Arp2/3 complex, Arp2 and Arp3, are proposed to form a pseudo actin dimer that nucleates actin polymerization. However, in the crystal structure of the inactive complex, they are too far apart to form such a nucleus. Here, we show using EM that yeast and bovine Arp2/3 complexes exist in a distribution among open, intermediate and closed conformations. The crystal structure docks well into the open conformation. The activator WASp binds at the cleft between Arp2 and Arp3, and all WASp-bound complexes are closed. The inhibitor coronin binds near the p35 subunit, and all coronin-bound complexes are open. Activating and loss-of-function mutations in the p35 subunit skew conformational distribution in opposite directions, closed and open, respectively. We conclude that WASp stabilizes p35-dependent closure of the complex, holding Arp2 and Arp3 closer together to nucleate an actin filament.}, author = {Rodal, Avital and Sokolova, Olga and Robins, Deborah and Daugherty, Karen and Hippenmeyer, Simon and Riezman, Howard and Grigorieff, Nikolaus and Goode, Bruce}, issn = {1545-9985}, journal = {Nature Structural and Molecular Biology}, number = {1}, pages = {26 -- 31}, publisher = {Nature Publishing Group}, title = {{Conformational changes in the Arp2 3 complex leading to actin nucleation}}, doi = {10.1038/nsmb870}, volume = {12}, year = {2004}, }