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Orlando BJ, Liao M. ABCG2 transports anticancer drugs via a closed-to-open switch. Nat Commun 2020; 11:2264. [PMID: 32385283 PMCID: PMC7210939 DOI: 10.1038/s41467-020-16155-2] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 04/16/2020] [Indexed: 12/18/2022] Open
Abstract
ABCG2 is an ABC transporter that extrudes a variety of compounds from cells, and presents an obstacle in treating chemotherapy-resistant cancers. Despite recent structural insights, no anticancer drug bound to ABCG2 has been resolved, and the mechanisms of multidrug transport remain obscure. Such a gap of knowledge limits the development of novel compounds that block or evade this critical molecular pump. Here we present single-particle cryo-EM studies of ABCG2 in the apo state, and bound to the three structurally distinct chemotherapeutics. Without the binding of conformation-selective antibody fragments or inhibitors, the resting ABCG2 adopts a closed conformation. Our cryo-EM, biochemical, and functional analyses reveal the binding mode of three chemotherapeutic compounds, demonstrate how these molecules open the closed conformation of the transporter, and establish that imatinib is particularly effective in stabilizing the inward facing conformation of ABCG2. Together these studies reveal the previously unrecognized conformational cycle of ABCG2. ABCG2 is a human ABC transporter that actively extrudes a wide variety of compounds from cells but the mechanisms of multidrug transport remain obscure. Here authors present cryo-EM structures of ABCG2 in the apo state, and bound to the three structurally distinct chemotherapeutics and demonstrate how these molecules open the closed conformation of the transporter.
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Affiliation(s)
- Benjamin J Orlando
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.
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52
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Martin EC, Vicari C, Tsakou-Ngouafo L, Pontarotti P, Petrescu AJ, Schatz DG. Identification of RAG-like transposons in protostomes suggests their ancient bilaterian origin. Mob DNA 2020; 11:17. [PMID: 32399063 PMCID: PMC7204232 DOI: 10.1186/s13100-020-00214-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/14/2020] [Indexed: 12/27/2022] Open
Abstract
Background V(D) J recombination is essential for adaptive immunity in jawed vertebrates and is initiated by the RAG1-RAG2 endonuclease. The RAG1 and RAG2 genes are thought to have evolved from a RAGL (RAG-like) transposon containing convergently-oriented RAG1-like (RAG1L) and RAG2-like (RAG2L) genes. Elements resembling this presumptive evolutionary precursor have thus far only been detected convincingly in deuterostomes, leading to the model that the RAGL transposon first appeared in an early deuterostome. Results We have identified numerous RAGL transposons in the genomes of protostomes, including oysters and mussels (phylum Mollusca) and a ribbon worm (phylum Nemertea), and in the genomes of several cnidarians. Phylogenetic analyses are consistent with vertical evolution of RAGL transposons within the Bilateria clade and with its presence in the bilaterian ancestor. Many of the RAGL transposons identified in protostomes are intact elements containing convergently oriented RAG1L and RAG2L genes flanked by terminal inverted repeats (TIRs) and target site duplications with striking similarities with the corresponding elements in deuterostomes. In addition, protostome genomes contain numerous intact RAG1L-RAG2L adjacent gene pairs that lack detectable flanking TIRs. Domains and critical active site and structural amino acids needed for endonuclease and transposase activity are present and conserved in many of the predicted RAG1L and RAG2L proteins encoded in protostome genomes. Conclusions Active RAGL transposons were present in multiple protostome lineages and many were likely transmitted vertically during protostome evolution. It appears that RAGL transposons were broadly active during bilaterian evolution, undergoing multiple duplication and loss/fossilization events, with the RAGL genes that persist in present day protostomes perhaps constituting both active RAGL transposons and domesticated RAGL genes. Our findings raise the possibility that the RAGL transposon arose earlier in evolution than previously thought, either in an early bilaterian or prior to the divergence of bilaterians and non-bilaterians, and alter our understanding of the evolutionary history of this important group of transposons.
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Affiliation(s)
- Eliza C Martin
- 1Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, 060031 Bucharest, Romania
| | - Célia Vicari
- 2Evolutionary biology team, Aix Marseille Université IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France
| | - Louis Tsakou-Ngouafo
- 2Evolutionary biology team, Aix Marseille Université IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France
| | - Pierre Pontarotti
- 2Evolutionary biology team, Aix Marseille Université IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France.,SNC5039 CNRS, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
| | - Andrei J Petrescu
- 1Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, 060031 Bucharest, Romania
| | - David G Schatz
- 4Department of Immunobiology, Yale School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011 USA
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53
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Eldar A, Landa B, Shkolnisky Y. KLT picker: Particle picking using data-driven optimal templates. J Struct Biol 2020; 210:107473. [PMID: 32035993 DOI: 10.1016/j.jsb.2020.107473] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/21/2020] [Accepted: 01/24/2020] [Indexed: 11/15/2022]
Abstract
Particle picking is currently a critical step in the cryo-EM single particle reconstruction pipeline. Despite extensive work on this problem, for many data sets it is still challenging, especially for low SNR micrographs. We present the KLT (Karhunen Loeve Transform) picker, which is fully automatic and requires as an input only the approximated particle size. In particular, it does not require any manual picking. Our method is designed especially to handle low SNR micrographs. It is based on learning a set of optimal templates through the use of multi-variate statistical analysis via the Karhunen Loeve Transform. We evaluate the KLT picker on publicly available data sets and present high-quality results with minimal manual effort.
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Affiliation(s)
- Amitay Eldar
- Department of Applied Mathematics, School of Mathematical Sciences, Tel-Aviv University, Tel-Aviv, Israel.
| | - Boris Landa
- Department of Mathematics, Yale University, 10 Hillhouse Ave, New Haven, USA.
| | - Yoel Shkolnisky
- Department of Applied Mathematics, School of Mathematical Sciences, Tel-Aviv University, Tel-Aviv, Israel.
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54
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Sun A, Xu K, Liu H, Li H, Shi Y, Zhu X, Liang T, Li X, Cao X, Ji Y, Jiang T, Xu C, Liu X. The evolution of zebrafish RAG2 protein is required for adapting to the elevated body temperature of the higher endothermic vertebrates. Sci Rep 2020; 10:4126. [PMID: 32139788 PMCID: PMC7057966 DOI: 10.1038/s41598-020-61019-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/19/2020] [Indexed: 11/21/2022] Open
Abstract
The recombination activating gene (RAG or RAG1/RAG2 complex)-mediated adaptive immune system is a hallmark of jawed vertebrates. It has been reported that RAG originated in invertebrates. However, whether RAG further evolved once it arose in jawed vertebrates remains largely unknown. Here, we found that zebrafish RAG (zRAG) had a lower activity than mouse RAG (mRAG). Intriguingly, the attenuated stability of zebrafish RAG2 (zRAG2), but not zebrafish RAG1, caused the reduced V(D)J recombination efficiency compared to mRAG at 37 °C which are the body temperature of most endotherms except birds. Importantly, the lower temperature 28 °C, which is the best temperature for zebrafish growth, made the recombination efficiency of zRAG similar to that of mRAG by improving the stability of zRAG2. Consistent with the prementioned observation, the V(D)J recombination of Rag2KI/KI mice, which zRAG2 was substituted for mRAG2, was also severely impaired. Unexpectedly, Rag2KI/KI mice developed cachexia syndromes accompanied by premature death. Taken together, our findings illustrate that the evolution of zebrafish RAG2 protein is required for adapting to the elevated body temperature of the higher endothermic vertebrates.
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Affiliation(s)
- Ao Sun
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Ke Xu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Haifeng Liu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Hua Li
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yaohuang Shi
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoyan Zhu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Tao Liang
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xinyue Li
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xianxia Cao
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yanhong Ji
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, 710061, China
| | - Taijiao Jiang
- Center of System Medicine, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Chenqi Xu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xiaolong Liu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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55
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Chi X, Li Y, Qiu X. V(D)J recombination, somatic hypermutation and class switch recombination of immunoglobulins: mechanism and regulation. Immunology 2020; 160:233-247. [PMID: 32031242 DOI: 10.1111/imm.13176] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 12/30/2019] [Accepted: 01/08/2020] [Indexed: 02/06/2023] Open
Abstract
Immunoglobulins emerging from B lymphocytes and capable of recognizing almost all kinds of antigens owing to the extreme diversity of their antigen-binding portions, known as variable (V) regions, play an important role in immune responses. The exons encoding the V regions are known as V (variable), D (diversity), or J (joining) genes. V, D, J segments exist as multiple copy arrays on the chromosome. The recombination of the V(D)J gene is the key mechanism to produce antibody diversity. The recombinational process, including randomly choosing a pair of V, D, J segments, introducing double-strand breaks adjacent to each segment, deleting (or inverting in some cases) the intervening DNA and ligating the segments together, is defined as V(D)J recombination, which contributes to surprising immunoglobulin diversity in vertebrate immune systems. To enhance both the ability of immunoglobulins to recognize and bind to foreign antigens and the effector capacities of the expressed antibodies, naive B cells will undergo class switching recombination (CSR) and somatic hypermutation (SHM). However, the genetics mechanisms of V(D)J recombination, CSR and SHM are not clear. In this review, we summarize the major progress in mechanism studies of immunoglobulin V(D)J gene recombination and CSR as well as SHM, and their regulatory mechanisms.
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Affiliation(s)
- Xiying Chi
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
| | - Yue Li
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
| | - Xiaoyan Qiu
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
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56
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Cutting antiparallel DNA strands in a single active site. Nat Struct Mol Biol 2020; 27:119-126. [PMID: 32015552 PMCID: PMC7015813 DOI: 10.1038/s41594-019-0363-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 12/13/2019] [Indexed: 01/17/2023]
Abstract
A single enzyme active site that catalyzes multiple reactions is a well-established biochemical theme, but how one nuclease site cleaves both DNA strands of a double helix has not been well understood. In analyzing site-specific DNA cleavage by the mammalian RAG1-RAG2 recombinase, which initiates V(D)J recombination, we find that the active site is reconfigured for the two consecutive reactions and the DNA double helix adopts drastically different structures. For initial nicking of the DNA, a locally unwound and unpaired DNA duplex forms a zipper via alternating interstrand base stacking, rather than melting as generally thought. The second strand cleavage and formation of a hairpin-DNA product requires a global scissor-like movement of protein and DNA, delivering the scissile phosphate into the rearranged active site.
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57
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How mouse RAG recombinase avoids DNA transposition. Nat Struct Mol Biol 2020; 27:127-133. [PMID: 32015553 PMCID: PMC8291384 DOI: 10.1038/s41594-019-0366-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 12/17/2019] [Indexed: 11/12/2022]
Abstract
The RAG1-RAG2 recombinase (RAG) cleaves DNA to initiate V(D)J recombination. But RAG also belongs to the RNH-type transposase family. To learn how RAG-catalyzed transposition is inhibited in developing lymphocytes, we determined the structure of a DNA strand-transfer complex of mouse RAG at 3.1 Å resolution. The target DNA is a T form (T for transpositional target), which contains two >80° kinks towards the minor groove, only 3 bp apart. RAG2, a late evolutionary addition in V(D)J recombination, appears to enforce the sharp kinks and additional inter-segment twisting in target DNA and thus attenuate unwanted transposition. In contrast to strand-transfer complexes of genuine transposases, where severe kinks occur at the integration sites of target DNA and thus prevent the reverse reaction, the sharp kink with RAG is 1 bp away from the integration site. As a result, RAG efficiently catalyzes the disintegration reaction that restores the RSS (donor) and target DNA.
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58
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Tao X, Yuan S, Chen F, Gao X, Wang X, Yu W, Liu S, Huang Z, Chen S, Xu A. Functional requirement of terminal inverted repeats for efficient ProtoRAG activity reveals the early evolution of V(D)J recombination. Natl Sci Rev 2020; 7:403-417. [PMID: 34692056 PMCID: PMC8289069 DOI: 10.1093/nsr/nwz179] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/31/2019] [Accepted: 11/08/2019] [Indexed: 11/30/2022] Open
Abstract
The discovery of ProtoRAG in amphioxus indicated that vertebrate RAG recombinases originated from an ancient transposon. However, the sequences of ProtoRAG terminal inverted repeats (TIRs) were obviously dissimilar to the consensus sequence of mouse 12/23RSS and recombination mediated by ProtoRAG or RAG made them incompatible with each other. Thus, it is difficult to determine whether or how 12/23RSS persisted in the vertebrate RAG system that evolved from the TIRs of ancient RAG transposons. Here, we found that the activity of ProtoRAG is highly dependent on its asymmetric 5′TIR and 3′TIR, which are composed of conserved TR1 and TR5 elements and a partially conserved TRsp element of 27/31 bp to separate them. Similar to the requirements for the recombination signal sequences (RSSs) of RAG recombinase, the first CAC in TR1, the three dinucleotides in TR5 and the specific length of the partially conserved TRsp are important for the efficient recombination activity of ProtoRAG. In addition, the homologous sequences flanking the signal sequences facilitate ProtoRAG- but not RAG-mediated recombination. In addition to the diverged TIRs, two differentiated functional domains in BbRAG1L were defined to coordinate with the divergence between TIRs and RSSs. One of these is the CTT* domain, which facilitates the specific TIR recognition of the BbRAGL complex, and the other is NBD*, which is responsible for DNA binding and the protein stabilization of the BbRAGL complex. Thus, our findings reveal that the functional requirement for ProtoRAG TIRs is similar to that for RSS in RAG-mediated recombination, which not only supports the common origin of ProtoRAG TIRs and RSSs from the asymmetric TIRs of ancient RAG transposons, but also reveals the development of RAG and RAG-like machineries during chordate evolution.
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Affiliation(s)
- Xin Tao
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shaochun Yuan
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Fan Chen
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xiaoman Gao
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xinli Wang
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wenjuan Yu
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Song Liu
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Ziwen Huang
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shangwu Chen
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Anlong Xu
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.,School of Life Sciences, Beijing University of Chinese Medicine, Beijing 100029, China
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59
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Wang J, Su Y, Iacob RE, Engen JR, Springer TA. General structural features that regulate integrin affinity revealed by atypical αVβ8. Nat Commun 2019; 10:5481. [PMID: 31792290 PMCID: PMC6889490 DOI: 10.1038/s41467-019-13248-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/22/2019] [Indexed: 01/16/2023] Open
Abstract
Integrin αVβ8, which like αVβ6 functions to activate TGF-βs, is atypical. Its β8 subunit binds to a distinctive cytoskeleton adaptor and does not exhibit large changes in conformation upon binding to ligand. Here, crystal structures, hydrogen-deuterium exchange dynamics, and affinity measurements on mutants are used to compare αVβ8 and αVβ6. Lack of a binding site for one of three βI domain divalent cations and a unique β6-α7 loop conformation in β8 facilitate movements of the α1 and α1’ helices at the ligand binding pocket toward the high affinity state, without coupling to β6-α7 loop reshaping and α7-helix pistoning that drive large changes in βI domain-hybrid domain orientation seen in other integrins. Reciprocal swaps between β6 and β8 βI domains increase affinity of αVβ6 and decrease affinity of αVβ8 and define features that regulate affinity of the βI domain and its coupling to the hybrid domain. The activation mechanism of integrin αVβ8 differs from other integrins. Combining X-ray crystallography, hydrogen deuterium exchange mass spectrometry and mutation, the authors reveal structural features responsible for these differences and provide insights into how typical integrins are regulated.
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Affiliation(s)
- Jianchuan Wang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Yang Su
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Roxana E Iacob
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA. .,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
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60
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Mușat MG, Nițulescu GM, Surleac M, Tsatsakis A, Spandidos DA, Margină D. HIV‑1 integrase inhibitors targeting various DDE transposases: Retroviral integration versus RAG‑mediated recombination (Review). Mol Med Rep 2019; 20:4749-4762. [PMID: 31702817 PMCID: PMC6854553 DOI: 10.3892/mmr.2019.10777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 10/25/2019] [Indexed: 12/18/2022] Open
Abstract
Transposases are ubiquitous mobile genetic elements responsible for genome development, driving rearrangements, such as insertions, deletions and translocations. Across species evolution, some transposases are tamed by their host and are made part of complex cellular systems. The proliferation of retroviruses is also dependent on transposase related enzymes termed integrases. Recombination‑activating gene protein (RAG)1 and metnase are just two examples of transposase domestication and together with retroviral integrases (INs), they belong to the DDE polynucleotidyl transferases superfamily. They share mechanistic and structural features linked to the RNase H‑like fold, harboring a DDE(D) metal dependent catalytic motif. Recent antiretroviral compounds target the catalytic domain of integrase, but they also have the potential of inhibiting other related enzymes. In this review, we report the activity of different classes of integrase inhibitors on various DDE transposases. Computational simulations are useful to predict the extent of off‑target activity and have been employed to study the interactions between RAG1 recombinase and compounds from three different pharmacologic classes. We demonstrate that strand‑transfer inhibitors display a higher affinity towards the RAG1 RNase H domain, as suggested by experimental data compared to allosteric inhibitors. While interference with RAG1 and 2 recombination is associated with a negative impact on immune function, the inhibition of metnase or HTLV‑1 integrase opens the way for the development of novel therapies for refractory cancers.
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Affiliation(s)
- Mihaela Georgiana Mușat
- Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 020956 Bucharest, Romania
| | - George Mihai Nițulescu
- Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 020956 Bucharest, Romania
| | - Marius Surleac
- National Institute for Infectious Diseases ‘Matei Bals’, 021105 Bucharest, Romania
| | - Aristidis Tsatsakis
- Department of Forensic Sciences and Toxicology, School of Medicine, University of Crete, 71003 Heraklion, Greece
| | - Demetrios A. Spandidos
- Laboratory of Clinical Virology, School of Medicine, University of Crete, 71003 Heraklion, Greece
| | - Denisa Margină
- Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 020956 Bucharest, Romania
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Arinkin V, Smyshlyaev G, Barabas O. Jump ahead with a twist: DNA acrobatics drive transposition forward. Curr Opin Struct Biol 2019; 59:168-177. [PMID: 31590109 PMCID: PMC6900584 DOI: 10.1016/j.sbi.2019.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/27/2019] [Accepted: 08/29/2019] [Indexed: 11/29/2022]
Abstract
Transposases move discrete pieces of DNA between genomic locations and had a profound impact on evolution. They drove the emergence of important biological functions and are the most frequent proteins encoded in modern genomes. Yet, the molecular principles of their actions have remained largely unclear. Here we review recent structural studies of transposase-DNA complexes and related cellular machineries, which provided unmatched mechanistic insights. We highlight how transposases introduce major DNA twists and kinks at various stages of their reaction and discuss the functional impact of these astounding DNA acrobatics on several aspects of transposition. By comparison with distantly related DNA recombination systems, we propose that forcing DNA into unnatural shapes may be a general strategy to drive rearrangements forward.
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Affiliation(s)
- Vladimir Arinkin
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Georgy Smyshlyaev
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, UK
| | - Orsolya Barabas
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
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62
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Mika J, Kabacik S, Badie C, Polanska J, Candéias SM. Germline DNA Retention in Murine and Human Rearranged T Cell Receptor Gene Coding Joints: Alternative Recombination Signal Sequences and V(D)J Recombinase Errors. Front Immunol 2019; 10:2637. [PMID: 31781122 PMCID: PMC6857471 DOI: 10.3389/fimmu.2019.02637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 10/24/2019] [Indexed: 12/02/2022] Open
Abstract
The genes coding for the antigenic T cell receptor (TR) subunits are assembled in thymocytes from discrete V, D, and J genes by a site-specific recombination process. A tight control of this activity is required to prevent potentially detrimental recombination events. V, D, and J genes are flanked by semi-conserved nucleotide motives called recombination signal sequences (RSSs). V(D)J recombination is initiated by the precise introduction of a DNA double-strand break exactly at the border of the genes and their RSSs by the RAG recombinase. RSSs are therefore physically separated from the coding region of the genes before assembly of a rearranged TR gene. During a high throughput profiling of TRB genes in mice, we identified rearranged TRB genes in which part or all of a flanking RSS was retained in V-D or D-J coding joints. In some instances, this retention of germline DNA resulted from the use of an upstream alternative RSS. However, we also identified TRB sequences where retention of germline DNA occurred in the absence of alternative RSS, suggesting that RAG activity was mis-targeted during recombination. Similar events were also identified in human rearranged TRB and TRG genes. The use of alternative RSSs during V(D)J recombination illustrates the complexity of RAG-RSSs interactions during V(D)J recombination. While the frequency of errors resulting from mis-targeted RAG activity is very low, we believe that these RAG errors may be at the origin of oncogenic translocations and are a threat for genetic stability in developing lymphocytes.
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Affiliation(s)
- Justyna Mika
- Data Mining Division, Silesian University of Technology, Gliwice, Poland
| | - Sylwia Kabacik
- Cancer Mechanisms and Biomarkers Group, Radiation Effects Department, Centre for Radiation, Chemical and Environmental Hazards Public Health England Chilton, Didcot, United Kingdom
| | - Christophe Badie
- Cancer Mechanisms and Biomarkers Group, Radiation Effects Department, Centre for Radiation, Chemical and Environmental Hazards Public Health England Chilton, Didcot, United Kingdom
| | - Joanna Polanska
- Data Mining Division, Silesian University of Technology, Gliwice, Poland
| | - Serge M Candéias
- Université Grenoble Alpes, CEA, CNRS, IRIG-LCBM, Grenoble, France
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64
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Liu C, Yang Y, Schatz DG. Structures of a RAG-like transposase during cut-and-paste transposition. Nature 2019; 575:540-544. [PMID: 31723264 PMCID: PMC6872938 DOI: 10.1038/s41586-019-1753-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 09/30/2019] [Indexed: 12/27/2022]
Abstract
Transposons have had a pivotal role in genome evolution1 and are believed to be the evolutionary progenitors of the RAG1-RAG2 recombinase2, an essential component of the adaptive immune system in jawed vertebrates3. Here we report one crystal structure and five cryo-electron microscopy structures of Transib4,5, a RAG1-like transposase from Helicoverpa zea, that capture the entire transposition process from the apo enzyme to the terminal strand transfer complex with transposon ends covalently joined to target DNA, at resolutions of 3.0-4.6 Å. These structures reveal a butterfly-shaped complex that undergoes two cycles of marked conformational changes in which the 'wings' of the transposase unfurl to bind substrate DNA, close to execute cleavage, open to release the flanking DNA and close again to capture and attack target DNA. Transib possesses unique structural elements that compensate for the absence of a RAG2 partner, including a loop that interacts with the transposition target site and an accordion-like C-terminal tail that elongates and contracts to help to control the opening and closing of the enzyme and assembly of the active site. Our findings reveal the detailed reaction pathway of a eukaryotic cut-and-paste transposase and illuminate some of the earliest steps in the evolution of the RAG recombinase.
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Affiliation(s)
- Chang Liu
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Yang Yang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
| | - David G Schatz
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA.
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Structure of a P element transposase-DNA complex reveals unusual DNA structures and GTP-DNA contacts. Nat Struct Mol Biol 2019; 26:1013-1022. [PMID: 31659330 DOI: 10.1038/s41594-019-0319-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/11/2019] [Indexed: 01/19/2023]
Abstract
P element transposase catalyzes the mobility of P element DNA transposons within the Drosophila genome. P element transposase exhibits several unique properties, including the requirement for a guanosine triphosphate cofactor and the generation of long staggered DNA breaks during transposition. To gain insights into these features, we determined the atomic structure of the Drosophila P element transposase strand transfer complex using cryo-EM. The structure of this post-transposition nucleoprotein complex reveals that the terminal single-stranded transposon DNA adopts unusual A-form and distorted B-form helical geometries that are stabilized by extensive protein-DNA interactions. Additionally, we infer that the bound guanosine triphosphate cofactor interacts with the terminal base of the transposon DNA, apparently to position the P element DNA for catalysis. Our structure provides the first view of the P element transposase superfamily, offers new insights into P element transposition and implies a transposition pathway fundamentally distinct from other cut-and-paste DNA transposases.
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66
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Zhang Y, Zhang X, Ba Z, Liang Z, Dring EW, Hu H, Lou J, Kyritsis N, Zurita J, Shamim MS, Presser Aiden A, Lieberman Aiden E, Alt FW. The fundamental role of chromatin loop extrusion in physiological V(D)J recombination. Nature 2019; 573:600-604. [PMID: 31511698 PMCID: PMC6867615 DOI: 10.1038/s41586-019-1547-y] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/12/2019] [Indexed: 11/24/2022]
Abstract
RAG endonuclease initiates IgH locus (Igh) V(D)J assembly in progenitor (pro)-B cells by joining Ds to JHs, before joining upstream VHs to DJH intermediates1. In mouse pro-B cells, the CTCF-binding element (CBE)-anchored chromatin loop domain2 at the 3’end of Igh contains an internal sub-domain spanning the 5’CBE anchor (IGCR1)3, the DHs, and a RAG-bound recombination center (RC)4. The RC comprises JH-proximal D (DQ52), 4 JHs, and the intronic enhancer (“iEμ”)5. Robust RAG cleavage is restricted to paired V(D)J segments flanked by complementary recombination signal sequences (12RSSs and 23RSSs)6. Ds are flanked downstream and upstream by 12RSSs that, respectively, mediate deletional joining with convergently-oriented JH-23RSSs and VH-23RSSs6. Despite 12/23 compatibility, inversional D to JH joining via upstream D-12RSSs is rare7,8. Plasmid-based assays attributed lack of inversional D to JH joining to sequence-based preference for downstream D-12RSSs9, as opposed to putative linear scanning mechanisms10,11. Given recent findings that RAG linearly scans convergent CBE-anchored chromatin loops4,12-14, potentially formed by cohesin-mediated loop extrusion15-18, we revisited a scanning role. Here, we report that JH-23RSS chromosomal orientation programs RC-bound RAG to linearly scan upstream chromatin in the 3’Igh sub-domain for convergently-oriented D-12RSSs and, thereby, to mediate deletional joining of all Ds, except RC-based DQ52 that joins by a diffusion-related mechanism. In a DQ52-based RC, formed in the absence of JHs, RAG bound by the downstream DQ52-RSS scans the downstream constant region exon-containing 3’Igh sub-domain in which scanning can be impeded by targeted nuclease-dead Cas9 (dCas9) binding, by transcription through repetitive Igh switch sequences, and by the 3’Igh CBE-based loop anchor. Notably, each scanning impediment focally increases RAG activity on potential substrate sequences within the impeded region. High resolution mapping of RC chromatin interactions reveals that such focal RAG targeting is associated with corresponding impediments to the loop extrusion process that drives chromatin past RC-bound RAG.
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Affiliation(s)
- Yu Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA.,Center for Immunobiology, Department of Biomedical Sciences, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, MI, USA.,Center for Immunobiology, Department of Biomedical Sciences, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, MI, USA
| | - Xuefei Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Zhaoqing Ba
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Zhuoyi Liang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Edward W Dring
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Hongli Hu
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Jiangman Lou
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Nia Kyritsis
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Jeffrey Zurita
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston, MA, USA
| | - Muhammad S Shamim
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Bioengineering, Rice University, Houston, TX, USA.,Department of Computer Science, Rice University, Houston, TX, USA.,Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Aviva Presser Aiden
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Bioengineering, Rice University, Houston, TX, USA.,Department of Pediatrics, Texas Children's Hospital, Houston, TX, USA
| | - Erez Lieberman Aiden
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Computer Science, Rice University, Houston, TX, USA.,Center for Theoretical Biological Physics, Rice University, Houston, TX, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA. .,Department of Genetics, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Boston, MA, USA.
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67
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Mutirangura A. A Hypothesis to Explain How the DNA of Elderly People Is Prone to Damage: Genome-Wide Hypomethylation Drives Genomic Instability in the Elderly by Reducing Youth-Associated Gnome-Stabilizing DNA Gaps. Epigenetics 2019. [DOI: 10.5772/intechopen.83372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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68
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Affiliation(s)
- Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, MD, USA
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
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69
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Abstract
While widespread genome sequencing ushers in a new era of preventive medicine, the tools for predictive genomics are still lacking. Time and resource limitations mean that human diseases remain uncharacterized because of an inability to predict clinically relevant genetic variants. A strategy of targeting highly conserved protein regions is used commonly in functional studies. However, this benefit is lost for rare diseases where the attributable genes are mostly conserved. An immunological disorder exemplifying this challenge occurs through damaging mutations in RAG1 and RAG2 which presents at an early age with a distinct phenotype of life-threatening immunodeficiency or autoimmunity. Many tools exist for variant pathogenicity prediction, but these cannot account for the probability of variant occurrence. Here, we present a method that predicts the likelihood of mutation for every amino acid residue in the RAG1 and RAG2 proteins. Population genetics data from approximately 146,000 individuals was used for rare variant analysis. Forty-four known pathogenic variants reported in patients and recombination activity measurements from 110 RAG1/2 mutants were used to validate calculated scores. Probabilities were compared with 98 currently known human cases of disease. A genome sequence dataset of 558 patients who have primary immunodeficiency but that are negative for RAG deficiency were also used as validation controls. We compared the difference between mutation likelihood and pathogenicity prediction. Our method builds a map of most probable mutations allowing pre-emptive functional analysis. This method may be applied to other diseases with hopes of improving preparedness for clinical diagnosis.
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70
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Structure and mechanism of the cation-chloride cotransporter NKCC1. Nature 2019; 572:488-492. [PMID: 31367042 DOI: 10.1038/s41586-019-1438-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/24/2019] [Indexed: 01/01/2023]
Abstract
Cation-chloride cotransporters (CCCs) mediate the electroneutral transport of chloride, potassium and/or sodium across the membrane. They have critical roles in regulating cell volume, controlling ion absorption and secretion across epithelia, and maintaining intracellular chloride homeostasis. These transporters are primary targets for some of the most commonly prescribed drugs. Here we determined the cryo-electron microscopy structure of the Na-K-Cl cotransporter NKCC1, an extensively studied member of the CCC family, from Danio rerio. The structure defines the architecture of this protein family and reveals how cytosolic and transmembrane domains are strategically positioned for communication. Structural analyses, functional characterizations and computational studies reveal the ion-translocation pathway, ion-binding sites and key residues for transport activity. These results provide insights into ion selectivity, coupling and translocation, and establish a framework for understanding the physiological functions of CCCs and interpreting disease-related mutations.
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71
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Hickman AB, Voth AR, Ewis H, Li X, Craig NL, Dyda F. Structural insights into the mechanism of double strand break formation by Hermes, a hAT family eukaryotic DNA transposase. Nucleic Acids Res 2019; 46:10286-10301. [PMID: 30239795 PMCID: PMC6212770 DOI: 10.1093/nar/gky838] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/07/2018] [Indexed: 12/12/2022] Open
Abstract
Some DNA transposons relocate from one genomic location to another using a mechanism that involves generating double-strand breaks at their transposon ends by forming hairpins on flanking DNA. The same double-strand break mode is employed by the V(D)J recombinase at signal-end/coding-end junctions during the generation of antibody diversity. How flanking hairpins are formed during DNA transposition has remained elusive. Here, we describe several co-crystal structures of the Hermes transposase bound to DNA that mimics the reaction step immediately prior to hairpin formation. Our results reveal a large DNA conformational change between the initial cleavage step and subsequent hairpin formation that changes which strand is acted upon by a single active site. We observed that two factors affect the conformational change: the complement of divalent metal ions bound by the catalytically essential DDE residues, and the identity of the –2 flanking base pair. Our data also provides a mechanistic link between the efficiency of hairpin formation (an A:T basepair is favored at the –2 position) and Hermes' strong target site preference. Furthermore, we have established that the histidine residue within a conserved C/DxxH motif present in many transposase families interacts directly with the scissile phosphate, suggesting a crucial role in catalysis.
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Affiliation(s)
- Alison B Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrea Regier Voth
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hosam Ewis
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xianghong Li
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nancy L Craig
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Rasila TS, Pulkkinen E, Kiljunen S, Haapa-Paananen S, Pajunen MI, Salminen A, Paulin L, Vihinen M, Rice PA, Savilahti H. Mu transpososome activity-profiling yields hyperactive MuA variants for highly efficient genetic and genome engineering. Nucleic Acids Res 2019; 46:4649-4661. [PMID: 29294068 PMCID: PMC5961161 DOI: 10.1093/nar/gkx1281] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/21/2017] [Indexed: 11/22/2022] Open
Abstract
The phage Mu DNA transposition system provides a versatile species non-specific tool for molecular biology, genetic engineering and genome modification applications. Mu transposition is catalyzed by MuA transposase, with DNA cleavage and integration reactions ultimately attaching the transposon DNA to target DNA. To improve the activity of the Mu DNA transposition machinery, we mutagenized MuA protein and screened for hyperactivity-causing substitutions using an in vivo assay. The individual activity-enhancing substitutions were mapped onto the MuA–DNA complex structure, containing a tetramer of MuA transposase, two Mu end segments and a target DNA. This analysis, combined with the varying effect of the mutations in different assays, implied that the mutations exert their effects in several ways, including optimizing protein–protein and protein–DNA contacts. Based on these insights, we engineered highly hyperactive versions of MuA, by combining several synergistically acting substitutions located in different subdomains of the protein. Purified hyperactive MuA variants are now ready for use as second-generation tools in a variety of Mu-based DNA transposition applications. These variants will also widen the scope of Mu-based gene transfer technologies toward medical applications such as human gene therapy. Moreover, the work provides a platform for further design of custom transposases.
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Affiliation(s)
- Tiina S Rasila
- Division of Genetics and Physiology, Department of Biology, FI-20014 University of Turku, Turku, Finland.,Institute of Biotechnology, Viikki Biocenter, P. O. Box 56, FI-00014 University of Helsinki, Helsinki, Finland
| | - Elsi Pulkkinen
- Division of Genetics and Physiology, Department of Biology, FI-20014 University of Turku, Turku, Finland
| | - Saija Kiljunen
- Division of Genetics and Physiology, Department of Biology, FI-20014 University of Turku, Turku, Finland
| | - Saija Haapa-Paananen
- Division of Genetics and Physiology, Department of Biology, FI-20014 University of Turku, Turku, Finland
| | - Maria I Pajunen
- Division of Biochemistry and Biotechnology, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Anu Salminen
- Department of Biochemistry, FI-20014 University of Turku, Turku, Finland
| | - Lars Paulin
- Institute of Biotechnology, Viikki Biocenter, P. O. Box 56, FI-00014 University of Helsinki, Helsinki, Finland
| | - Mauno Vihinen
- Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Harri Savilahti
- Division of Genetics and Physiology, Department of Biology, FI-20014 University of Turku, Turku, Finland.,Institute of Biotechnology, Viikki Biocenter, P. O. Box 56, FI-00014 University of Helsinki, Helsinki, Finland
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73
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Giessen TW, Orlando BJ, Verdegaal AA, Chambers MG, Gardener J, Bell DC, Birrane G, Liao M, Silver PA. Large protein organelles form a new iron sequestration system with high storage capacity. eLife 2019; 8:46070. [PMID: 31282860 PMCID: PMC6668986 DOI: 10.7554/elife.46070] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 07/06/2019] [Indexed: 12/21/2022] Open
Abstract
Iron storage proteins are essential for cellular iron homeostasis and redox balance. Ferritin proteins are the major storage units for bioavailable forms of iron. Some organisms lack ferritins, and it is not known how they store iron. Encapsulins, a class of protein-based organelles, have recently been implicated in microbial iron and redox metabolism. Here, we report the structural and mechanistic characterization of a 42 nm two-component encapsulin-based iron storage compartment from Quasibacillus thermotolerans. Using cryo-electron microscopy and x-ray crystallography, we reveal the assembly principles of a thermostable T = 4 shell topology and its catalytic ferroxidase cargo and show interactions underlying cargo-shell co-assembly. This compartment has an exceptionally large iron storage capacity storing over 23,000 iron atoms. Our results reveal a new approach for survival in diverse habitats with limited or fluctuating iron availability via an iron storage system able to store 10 to 20 times more iron than ferritin. People often think of the cell as the basic unit of life. Despite this, individual cells are also subdivided into many compartments, called ‘organelles’ because they act like the internal organs of the cell. For example, organelles can break down nutrients, store information in the form of DNA, or help remove waste. Even bacterial cells, despite being smaller and simpler than most other cell types, contain organelle-like structures. These are tiny compartments, termed protein organelles, which are enclosed by ‘shells’ made from self-assembling proteins within the cell. Cells need iron to carry out the chemical reactions necessary for life. Iron is therefore an essential nutrient, but it can also be toxic if not stored properly inside the cell. Cells often solve this problem by locking iron away inside small, specialised protein cages called ferritins until it can be used. Most organisms, from humans to bacteria, have ferritins, but some do not, and the way these organisms store iron remains largely unknown. The bacterium Quasibacillus thermotolerans is an example of an organism that lacks ferritins. However, it does contain a recently discovered type of protein organelle, called an encapsulin. Giessen et al. wanted to find out more about the structure of this protein organelle, and to determine if it helped these bacteria store iron. Q. thermotolerans’ encapsulin turned out to be the largest of its kind discovered to date. Detailed imaging experiments, using a combination of electron microscopy and X-ray- based techniques, revealed that the protein shell of the encapsulin had an overall structure resembling chain mail and contained multiple pores. These pores were negatively charged, meaning that they could efficiently attract iron (which has a positive charge) and funnel it into the interior of the compartment. The compartment itself was able to store at least 20 times more iron than ferritins, making this encapsulin one of the most efficient methods of iron storage in any cell. These findings will help us better understand how bacteria that lack ferritins cope with the problem of iron storage. In the future, encapsulins could also be used as a target for new therapies to fight bacterial infections, or even as the building blocks for microscopic chemical reactors or ‘storage facilities’ in industrial applications.
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Affiliation(s)
- Tobias W Giessen
- Department of Systems Biology, Harvard Medical School, Boston, United States.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, United States.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, United States
| | - Benjamin J Orlando
- Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Andrew A Verdegaal
- Department of Systems Biology, Harvard Medical School, Boston, United States.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, United States
| | - Melissa G Chambers
- Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Jules Gardener
- Center for Nanoscale Systems, Harvard University, Cambridge, United States
| | - David C Bell
- Center for Nanoscale Systems, Harvard University, Cambridge, United States.,School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - Gabriel Birrane
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States
| | - Maofu Liao
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Pamela A Silver
- Department of Systems Biology, Harvard Medical School, Boston, United States
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74
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Lee JJ, Park IH, Rhee WJ, Kim HS, Shin JS. HMGB1 modulates the balance between senescence and apoptosis in response to genotoxic stress. FASEB J 2019; 33:10942-10953. [PMID: 31284735 DOI: 10.1096/fj.201900288r] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
High mobility group box-1 (HMGB1) is involved in various diseases and is associated with the resistance of many types of human cancers to chemotherapy; however, its role in cancer metastasis remains unexplored. This study examined the HMGB1 status of both highly and poorly metastatic cancer cells in response to genotoxic stress. The weakly and highly metastatic mouse melanoma cell lines (B16 vs. B16-F10), human melanoma cell lines (SK-MEL-28 vs. SK-MEL-24), colon cancer cell lines (DLD-1 vs. LS174T), and wild-type (WT) vs. HMGB1 knockout (KO) mouse embryonic fibroblasts (MEFs) were treated with doxorubicin (Dox) and camptothecin (CPT), and then cellular morphology, senescence-associated β-galactosidase staining, lactate dehydrogenase release, and caspase-3 activation were used to assess cell fate. To investigate the role of HMGB1 in p21 expression, HMGB1 and p21 expressions were examined by Western blotting, and the HMGB1-mediated p21 promoter luciferase assay was performed after small interfering RNA or overexpression of HMGB1 prior to Dox treatment. Although highly metastatic mouse melanoma B16-F10 cells preferred senescence, with persistent HMGB1 expression, poorly metastatic B16 cells entered apoptosis, with decreasing HMGB1 levels via cleavage under Dox treatment. Similarly, more metastatic human melanoma SK-MEL-24 and human colon cancer LS174T cells underwent senescence, whereas fewer metastatic melanoma SK-MEL-28 and DLD-1 cells exhibited apoptosis under Dox stimulation. In senescent B16-F10, SK-MEL-24, and LS174T cells treated with Dox, p21 levels were increased by persistent HMGB1 expression. Furthermore, HMGB1 depletion caused a senescence-apoptosis shift with p21 down-regulation in B16-F10 cells, and HMGB1 overexpression switched from apoptosis to senescence concomitantly with increased p21 expression in B16 cells after Dox treatment. The same effects were observed in both cell pairs of mouse melanoma and human colon cancer cells treated with CPT, another genotoxic stressor. Indeed, although WT MEF entered senescence accompanied by p21 increase, HMGB1 KO underwent apoptosis with p21 decrease by Dox treatment. In our cell model system, we demonstrated that highly metastatic cancer cells preferentially enter senescence, whereas apoptosis predominates in weakly metastatic cancer cells under genotoxic stress, which depends on the presence or absence of HMGB1, suggesting that the HMGB1-p21 axis is required for genotoxic stress-induced senescence. These findings suggest that HMGB1 modulation of cancers with different metastatic status could be a strategy for selectively enforcing tumor suppression.-Lee, J.-J., Park, I. H., Rhee, W. J., Kim, H. S., Shin, J.-S. HMGB1 modulates the balance between senescence and apoptosis in response to genotoxic stress.
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Affiliation(s)
- Je-Jung Lee
- Department of Microbiology, Yonsei University College of Medicine, Seoul, South Korea.,Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, South Korea
| | - In Ho Park
- Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, South Korea.,Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Woo Joong Rhee
- Department of Microbiology, Yonsei University College of Medicine, Seoul, South Korea.,Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, South Korea
| | - Hee Sue Kim
- Department of Microbiology, Yonsei University College of Medicine, Seoul, South Korea
| | - Jeon-Soo Shin
- Department of Microbiology, Yonsei University College of Medicine, Seoul, South Korea.,Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, South Korea.,Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, South Korea.,Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, South Korea
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75
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Duan J, Li J, Chen GL, Ge Y, Liu J, Xie K, Peng X, Zhou W, Zhong J, Zhang Y, Xu J, Xue C, Liang B, Zhu L, Liu W, Zhang C, Tian XL, Wang J, Clapham DE, Zeng B, Li Z, Zhang J. Cryo-EM structure of TRPC5 at 2.8-Å resolution reveals unique and conserved structural elements essential for channel function. SCIENCE ADVANCES 2019; 5:eaaw7935. [PMID: 31355338 PMCID: PMC6656536 DOI: 10.1126/sciadv.aaw7935] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/18/2019] [Indexed: 05/21/2023]
Abstract
The transient receptor potential canonical subfamily member 5 (TRPC5), one of seven mammalian TRPC members, is a nonselective calcium-permeant cation channel. TRPC5 is of considerable interest as a drug target in the treatment of progressive kidney disease, depression, and anxiety. Here, we present the 2.8-Å resolution cryo-electron microscopy (cryo-EM) structure of the mouse TRPC5 (mTRPC5) homotetramer. Comparison of the TRPC5 structure to previously determined structures of other TRPC and TRP channels reveals differences in the extracellular pore domain and in the length of the S3 helix. The disulfide bond at the extracellular side of the pore and a preceding small loop are essential elements for its proper function. This high-resolution structure of mTRPC5, combined with electrophysiology and mutagenesis, provides insight into the lipid modulation and gating mechanisms of the TRPC family of ion channels.
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Affiliation(s)
- Jingjing Duan
- Human Aging Research Institute (HARI), School of Life Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
- School of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Jian Li
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of the Ministry of Education, Gannan Medical University, Ganzhou 341000, China
- College of Pharmaceutical Sciences, Gannan Medical University, #1 Yixueyuan Road, Ganzhou, Jiangxi 341000, China
| | - Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Sichuan Province and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
- Department of Endocrinology, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, 646000, China
| | - Yan Ge
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Sichuan Province and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Jieyu Liu
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Sichuan Province and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Kechen Xie
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Sichuan Province and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Xiaogang Peng
- Key Laboratory of Molecular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Wei Zhou
- Key Laboratory of Molecular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Jianing Zhong
- College of Pharmaceutical Sciences, Gannan Medical University, #1 Yixueyuan Road, Ganzhou, Jiangxi 341000, China
| | - Yixing Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
| | - Jie Xu
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China
| | - Changhu Xue
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China
| | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lan Zhu
- School of Molecular Sciences and Biodesign Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
| | - Wei Liu
- School of Molecular Sciences and Biodesign Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
| | - Cheng Zhang
- Jiangxi Jmerry Biopharmaceutical Co. Ltd, Ganzhou, Jiangxi 341000, China
| | - Xiao-Li Tian
- Human Aging Research Institute (HARI), School of Life Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
| | - Jianbin Wang
- School of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
| | - David E. Clapham
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Sichuan Province and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
- Department of Endocrinology, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, 646000, China
- Corresponding author. (J.Z.); (Z.L.); (B.Z.)
| | - Zongli Li
- Howard Hughes Medical Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Corresponding author. (J.Z.); (Z.L.); (B.Z.)
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi 330031, China
- Corresponding author. (J.Z.); (Z.L.); (B.Z.)
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76
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Van den Eynde J, Crauwels A, Demaerel PG, Van Eycken L, Bullens D, Schrijvers R, Toelen J. YouTube Videos as a Source of Information About Immunology for Medical Students: Cross-Sectional Study. JMIR MEDICAL EDUCATION 2019; 5:e12605. [PMID: 31140440 PMCID: PMC6658288 DOI: 10.2196/12605] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 03/24/2019] [Accepted: 04/26/2019] [Indexed: 05/15/2023]
Abstract
BACKGROUND The use of the internet as a source of information has grown exponentially in the last decade. YouTube is currently the second most visited website and a major Web-based educational resource for medical students. OBJECTIVE The aim of this study was to evaluate the quality, accuracy, and attractiveness of the information acquired from YouTube videos about 2 central concepts in immunology. METHODS YouTube videos posted before August 27, 2018 were searched using selected keywords related to either antigen presentation or immunoglobulin gene rearrangement. Video characteristics were recorded, and the Video Power Index (VPI) was calculated. Videos were assessed using 5 validated scoring systems: understandability and attractiveness, reliability, content and comprehensiveness, global quality score (GQS), and a subjective score. Videos were categorized by educational usefulness and by source. RESULTS A total of 82 videos about antigen presentation and 70 about immunoglobulin gene rearrangement were analyzed. Videos had a mean understandability and attractiveness score of 6.57/8 and 5.84/8, content and comprehensiveness score of 9.84/20 and 5.84/20, reliability score of 1.65/4 and 1.53/4, GQS of 3.38/5 and 2.76/5, and subjective score of 2.00/3 and 2.00/3, respectively. The organized channels group tended to have the highest VPI and GQS. CONCLUSIONS YouTube can provide medical students with some useful information about immunology, although content wise it cannot substitute textbooks and academic courses. Students and teachers should be aware of the educational quality of available videos if they intend to use them in the context of blended learning.
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Affiliation(s)
| | | | | | | | - Dominique Bullens
- Faculty of Medicine, KU Leuven, Leuven, Belgium
- Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
- Division of Woman and Child, Department of Pediatrics, UZ Leuven, Leuven, Belgium
| | - Rik Schrijvers
- Faculty of Medicine, KU Leuven, Leuven, Belgium
- Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
- Division of Allergy and Clinical Immunology, Department of General Internal Medicine, UZ Leuven, Leuven, Belgium
| | - Jaan Toelen
- Faculty of Medicine, KU Leuven, Leuven, Belgium
- Division of Woman and Child, Department of Pediatrics, UZ Leuven, Leuven, Belgium
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
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77
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Zhang Y, Cheng TC, Huang G, Lu Q, Surleac MD, Mandell JD, Pontarotti P, Petrescu AJ, Xu A, Xiong Y, Schatz DG. Transposon molecular domestication and the evolution of the RAG recombinase. Nature 2019; 569:79-84. [PMID: 30971819 PMCID: PMC6494689 DOI: 10.1038/s41586-019-1093-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 03/07/2019] [Indexed: 12/11/2022]
Abstract
Domestication of a transposon (a DNA sequence that can change its position in a genome) to give rise to the RAG1-RAG2 recombinase (RAG) and V(D)J recombination, which produces the diverse repertoire of antibodies and T cell receptors, was a pivotal event in the evolution of the adaptive immune system of jawed vertebrates. The evolutionary adaptations that transformed the ancestral RAG transposase into a RAG recombinase with appropriately regulated DNA cleavage and transposition activities are not understood. Here, beginning with cryo-electron microscopy structures of the amphioxus ProtoRAG transposase (an evolutionary relative of RAG), we identify amino acid residues and domains the acquisition or loss of which underpins the propensity of RAG for coupled cleavage, its preference for asymmetric DNA substrates and its inability to perform transposition in cells. In particular, we identify two adaptations specific to jawed-vertebrates-arginine 848 in RAG1 and an acidic region in RAG2-that together suppress RAG-mediated transposition more than 1,000-fold. Our findings reveal a two-tiered mechanism for the suppression of RAG-mediated transposition, illuminate the evolution of V(D)J recombination and provide insight into the principles that govern the molecular domestication of transposons.
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Affiliation(s)
- Yuhang Zhang
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Tat Cheung Cheng
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | | | - Qingyi Lu
- Beijing University of Chinese Medicine, Beijing, China
| | - Marius D Surleac
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Jeffrey D Mandell
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Pierre Pontarotti
- Aix Marseille Univ IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France.,Centre National de la Recherche Scientifique, Marseille, France
| | - Andrei J Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Anlong Xu
- Beijing University of Chinese Medicine, Beijing, China. .,State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Higher Education Mega Center, Guangzhou, China.
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
| | - David G Schatz
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA.
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78
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Cut-and-Run: A Distinct Mechanism by which V(D)J Recombination Causes Genome Instability. Mol Cell 2019; 74:584-597.e9. [PMID: 30905508 PMCID: PMC6509286 DOI: 10.1016/j.molcel.2019.02.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 12/20/2018] [Accepted: 02/14/2019] [Indexed: 12/28/2022]
Abstract
V(D)J recombination is essential to generate antigen receptor diversity but is also a potent cause of genome instability. Many chromosome alterations that result from aberrant V(D)J recombination involve breaks at single recombination signal sequences (RSSs). A long-standing question, however, is how such breaks occur. Here, we show that the genomic DNA that is excised during recombination, the excised signal circle (ESC), forms a complex with the recombinase proteins to efficiently catalyze breaks at single RSSs both in vitro and in vivo. Following cutting, the RSS is released while the ESC-recombinase complex remains intact to potentially trigger breaks at further RSSs. Consistent with this, chromosome breaks at RSSs increase markedly in the presence of the ESC. Notably, these breaks co-localize with those found in acute lymphoblastic leukemia patients and occur at key cancer driver genes. We have named this reaction “cut-and-run” and suggest that it could be a significant cause of lymphocyte genome instability. A complex between the recombination by-product and RAGs triggers multiple DNA breaks The breaks co-localize with chromosome breakpoints in acute lymphoblastic leukemias The breaks occur at many frequently mutated genes in acute lymphoblastic leukemia Cut-and-run may underpin the most common types of lymphocyte chromosome instabilities
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79
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Li Y, Orlando BJ, Liao M. Structural basis of lipopolysaccharide extraction by the LptB 2FGC complex. Nature 2019; 567:486-490. [PMID: 30894744 PMCID: PMC6532066 DOI: 10.1038/s41586-019-1025-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/18/2019] [Indexed: 12/15/2022]
Abstract
In Gram-negative bacteria, lipopolysaccharide is essential for outer membrane formation and antibiotic resistance. The seven lipopolysaccharide transport (Lpt) proteins A-G move lipopolysaccharide from the inner to the outer membrane. The ATP-binding cassette transporter LptB2FG, which tightly associates with LptC, extracts lipopolysaccharide out of the inner membrane. The mechanism of the LptB2FG-LptC complex (LptB2FGC) and the role of LptC in lipopolysaccharide transport are poorly understood. Here we characterize the structures of LptB2FG and LptB2FGC in nucleotide-free and vanadate-trapped states, using single-particle cryo-electron microscopy. These structures resolve the bound lipopolysaccharide, reveal transporter-lipopolysaccharide interactions with side-chain details and uncover how the capture and extrusion of lipopolysaccharide are coupled to conformational rearrangements of LptB2FGC. LptC inserts its transmembrane helix between the two transmembrane domains of LptB2FG, which represents a previously unknown regulatory mechanism for ATP-binding cassette transporters. Our results suggest a role for LptC in achieving efficient lipopolysaccharide transport, by coordinating the action of LptB2FG in the inner membrane and Lpt protein interactions in the periplasm.
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Affiliation(s)
- Yanyan Li
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | | | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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80
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Jin Y, Lee A, Oh JH, Lee HW, Ha SJ. The R229Q mutation of Rag2 does not characterize severe immunodeficiency in mice. Sci Rep 2019; 9:4415. [PMID: 30872621 PMCID: PMC6418226 DOI: 10.1038/s41598-019-39496-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/27/2018] [Indexed: 02/05/2023] Open
Abstract
RAG1 or RAG2 mutations are associated with defects in V(D)J recombination activity, causing severe immunodeficiency with a wide spectrum of clinical phenotypes. A R229Q mutation of RAG2 was identified in patients with severe combined immunodeficiency (SCID) or Omenn syndrome (OS). Although some factors determining the clinical features between SCID and OS were not clear, the molecular mechanism of OS was studied in a mouse model in which an EGFP tag is fused to Rag2 with the R229Q mutation. To design the human disease model mimicking severe immunodeficiency, we generated Rag2-R229Q knock-in mice without an epitope tag. Mutant mice showed impaired T and B cell differentiation with reduced V(D)J recombination activity; however, the extent to which the R229Q mutation affects severe immunodeficiency was not severe. While Rag2-R229Q mutation under some conditions may cause severe immunological and clinical phenotypes similar to human SCID or OS, R229Q mutation per se did not cause severe immunodeficiency in mice, suggesting that additional factors other than R229Q mutation are required to induce severe immunodeficiency. Thus, our report implies that the effects of genetic background and/or a tagged protein sequence may alter the mouse immune system, revealing the mechanism of phenotypic heterogeneity arising from an identical mutation.
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Affiliation(s)
- Young Jin
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Ara Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Ja Hyun Oh
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Han-Woong Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea.
| | - Sang-Jun Ha
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea.
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81
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RAGs usurp cellular factors for both breaking and repairing. Blood 2019; 133:773-774. [DOI: 10.1182/blood-2019-01-892729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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82
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Profile of Hao Wu. Proc Natl Acad Sci U S A 2019; 116:1078-1080. [DOI: 10.1073/pnas.1821528116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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83
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Villa A, Notarangelo LD. RAG gene defects at the verge of immunodeficiency and immune dysregulation. Immunol Rev 2019; 287:73-90. [PMID: 30565244 PMCID: PMC6309314 DOI: 10.1111/imr.12713] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 08/21/2018] [Indexed: 12/18/2022]
Abstract
Mutations of the recombinase activating genes (RAG) in humans underlie a broad spectrum of clinical and immunological phenotypes that reflect different degrees of impairment of T- and B-cell development and alterations of mechanisms of central and peripheral tolerance. Recent studies have shown that this phenotypic heterogeneity correlates, albeit imperfectly, with different levels of recombination activity of the mutant RAG proteins. Furthermore, studies in patients and in newly developed animal models carrying hypomorphic RAG mutations have disclosed various mechanisms underlying immune dysregulation in this condition. Careful annotation of clinical outcome and immune reconstitution in RAG-deficient patients who have received hematopoietic stem cell transplantation has shown that progress has been made in the treatment of this disease, but new approaches remain to be tested to improve stem cell engraftment and durable immune reconstitution. Finally, initial attempts have been made to treat RAG deficiency with gene therapy.
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Affiliation(s)
- Anna Villa
- San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), Division of Regenerative Medicine, Stem Cell and Gene Therapy, San Raffaele Scientific Institute, Milan, Italy
- Milan Unit, Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Luigi D Notarangelo
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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84
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Structural basis of coreceptor recognition by HIV-1 envelope spike. Nature 2018; 565:318-323. [PMID: 30542158 PMCID: PMC6391877 DOI: 10.1038/s41586-018-0804-9] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/02/2018] [Indexed: 01/26/2023]
Abstract
HIV-1 envelope glycoprotein (Env), which consists of trimeric (gp160)3 cleaved to (gp120 and gp41)3, interacts with the primary receptor CD4 and a coreceptor (such as chemokine receptor CCR5) to fuse viral and target-cell membranes. The gp120-coreceptor interaction has previously been proposed as the most crucial trigger for unleashing the fusogenic potential of gp41. Here we report a cryo-electron microscopy structure of a full-length gp120 in complex with soluble CD4 and unmodified human CCR5, at 3.9 Å resolution. The V3 loop of gp120 inserts into the chemokine-binding pocket formed by seven transmembrane helices of CCR5, and the N terminus of CCR5 contacts the CD4-induced bridging sheet of gp120. CCR5 induces no obvious allosteric changes in gp120 that can propagate to gp41; it does bring the Env trimer close to the target membrane. The N terminus of gp120, which is gripped by gp41 in the pre-fusion or CD4-bound Env, flips back in the CCR5-bound conformation and may irreversibly destabilize gp41 to initiate fusion. The coreceptor probably functions by stabilizing and anchoring the CD4-induced conformation of Env near the cell membrane. These results advance our understanding of HIV-1 entry into host cells and may guide the development of vaccines and therapeutic agents.
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85
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A novel RAG1 mutation reveals a critical in vivo role for HMGB1/2 during V(D)J recombination. Blood 2018; 133:820-829. [PMID: 30538136 DOI: 10.1182/blood-2018-07-866939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/04/2018] [Indexed: 01/01/2023] Open
Abstract
The Recombination Activating Genes, RAG1 and RAG2, are essential for V(D)J recombination and adaptive immunity. Mutations in these genes often cause immunodeficiency, the severity of which reflects the importance of the altered residue or residues during recombination. Here, we describe a novel RAG1 mutation that causes immunodeficiency in an unexpected way: The mutated protein severely disrupts binding of the accessory protein, HMGB1. Although HMGB1 enhances RAG cutting in vitro, its role in vivo was controversial. We show here that reduced HMGB1 binding by the mutant protein dramatically reduces RAG cutting in vitro and almost completely eliminates recombination in vivo. The RAG1 mutation, R401W, places a bulky tryptophan opposite the binding site for HMG Box A at both 12- and 23-spacer recombination signal sequences, disrupting stable binding of HMGB1. Replacement of R401W with leucine and then lysine progressively restores HMGB1 binding, correlating with increased RAG cutting and recombination in vivo. We show further that knockdown of HMGB1 significantly reduces recombination by wild-type RAG1, whereas its re-addition restores recombination with wild-type, but not the mutant, RAG1 protein. Together, these data provide compelling evidence that HMGB1 plays a critical role during V(D)J recombination in vivo.
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86
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A clinical perspective on immunoglobulin heavy chain clonal heterogeneity in B cell acute lymphoblastic leukemia. Leuk Res 2018; 75:15-22. [DOI: 10.1016/j.leukres.2018.10.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/30/2018] [Accepted: 10/31/2018] [Indexed: 12/15/2022]
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87
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Structural gymnastics of RAG-mediated DNA cleavage in V(D)J recombination. Curr Opin Struct Biol 2018; 53:178-186. [PMID: 30476719 DOI: 10.1016/j.sbi.2018.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/05/2018] [Indexed: 11/22/2022]
Abstract
A hallmark of vertebrate immunity is the diverse repertoire of antigen-receptor genes that results from combinatorial splicing of gene coding segments by V(D)J recombination. The (RAG1-RAG2)2 endonuclease complex (RAG) specifically recognizes and cleaves a pair of recombination signal sequences (RSSs), 12-RSS and 23-RSS, via the catalytic steps of nicking and hairpin formation. Both RSSs immediately flank the coding end segments and are composed of a conserved heptamer, a conserved nonamer, and a non-conserved spacer of either 12 base pairs (bp) or 23 bp in between. A single RAG complex only synapses a 12-RSS and a 23-RSS, which was denoted the 12/23 rule, a dogma that ensures recombination between V, D and J segments, but not within the same type of segments. This review recapitulates current structural studies to highlight the conformational transformations in both the RAG complex and the RSS during the consecutive steps of catalysis. The emerging structural mechanism emphasizes distortion of intact RSS and nicked RSS exerted by a piston-like motion in RAG1 and by dimer closure, respectively. Bipartite recognition of heptamer and nonamer, flexibly linked nonamer-binding domain dimer relatively to the heptamer recognition region dimer, and RSS plasticity and bending by HMGB1 together contribute to the molecular basis of the 12/23 rule in the RAG molecular machine.
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88
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Sui X, Arlt H, Brock KP, Lai ZW, DiMaio F, Marks DS, Liao M, Farese RV, Walther TC. Cryo-electron microscopy structure of the lipid droplet-formation protein seipin. J Cell Biol 2018; 217:4080-4091. [PMID: 30327422 PMCID: PMC6279392 DOI: 10.1083/jcb.201809067] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 01/11/2023] Open
Abstract
Sui et al. report the cryo-EM structure of the conserved luminal domain of the lipid droplet (LD)-formation protein seipin. The structure reveals key features of this domain and suggests a new model for seipin’s role in LD formation. Metabolic energy is stored in cells primarily as triacylglycerols in lipid droplets (LDs), and LD dysregulation leads to metabolic diseases. The formation of monolayer-bound LDs from the endoplasmic reticulum (ER) bilayer is poorly understood, but the ER protein seipin is essential to this process. In this study, we report a cryo–electron microscopy structure and functional characterization of Drosophila melanogaster seipin. The structure reveals a ring-shaped dodecamer with the luminal domain of each monomer resolved at ∼4.0 Å. Each luminal domain monomer exhibits two distinctive features: a hydrophobic helix (HH) positioned toward the ER bilayer and a β-sandwich domain with structural similarity to lipid-binding proteins. This structure and our functional testing in cells suggest a model in which seipin oligomers initially detect forming LDs in the ER via HHs and subsequently act as membrane anchors to enable lipid transfer and LD growth.
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Affiliation(s)
- Xuewu Sui
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Henning Arlt
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Kelly P Brock
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Zon Weng Lai
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Frank DiMaio
- Department of Biochemistry and Institute of Protein Design, University of Washington, Seattle, WA
| | - Debora S Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Robert V Farese
- Department of Cell Biology, Harvard Medical School, Boston, MA .,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA.,Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, MA
| | - Tobias C Walther
- Department of Cell Biology, Harvard Medical School, Boston, MA .,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA.,Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, MA.,Howard Hughes Medical Institute, Boston, MA
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89
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Structure of the mammalian TRPM7, a magnesium channel required during embryonic development. Proc Natl Acad Sci U S A 2018; 115:E8201-E8210. [PMID: 30108148 PMCID: PMC6126765 DOI: 10.1073/pnas.1810719115] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The transient receptor potential ion channel subfamily M, member 7 (TRPM7), is a ubiquitously expressed protein that is required for mouse embryonic development. TRPM7 contains both an ion channel and an α-kinase. The channel domain comprises a nonselective cation channel with notable permeability to Mg2+ and Zn2+ Here, we report the closed state structures of the mouse TRPM7 channel domain in three different ionic conditions to overall resolutions of 3.3, 3.7, and 4.1 Å. The structures reveal key residues for an ion binding site in the selectivity filter, with proposed partially hydrated Mg2+ ions occupying the center of the conduction pore. In high [Mg2+], a prominent external disulfide bond is found in the pore helix, which is essential for ion channel function. Our results provide a structural framework for understanding the TRPM1/3/6/7 subfamily and extend the knowledge base upon which to study the diversity and evolution of TRP channels.
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90
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Lin SG, Ba Z, Alt FW, Zhang Y. RAG Chromatin Scanning During V(D)J Recombination and Chromatin Loop Extrusion are Related Processes. Adv Immunol 2018; 139:93-135. [PMID: 30249335 DOI: 10.1016/bs.ai.2018.07.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An effective adaptive immune system depends on the ability of developing B and T cells to generate diverse immunoglobulin (Ig) and T cell receptor repertoires, respectively. Such diversity is achieved through a programmed somatic recombination process whereby germline V, D, and J segments of antigen receptor loci are assembled to form the variable region V(D)J exons of Ig and TCRs. Studies of this process, termed V(D)J recombination, have provided key insights into our understanding of a variety of general gene regulatory and DNA repair processes over the last several decades. V(D)J recombination is initiated by the RAG endonuclease which generates DNA double-stranded breaks at the borders of V, D, and J segments. In this review, we cover recent work that has elucidated RAG structure and work that revealed that RAG has a novel chromatin scanning activity, likely mediated by chromatin loop extrusion, that contributes to its ability to locate V, D, J gene segment substrates within large chromosomal loop domains bounded by CTCF-binding elements (CBEs). This latter function, coupled with the role CBE-based chromatin loop domains and subdomains within them play in focusing V(D)J recombination activity within antigen receptor loci, provide mechanistic explanations for long-standing questions regarding V(D)J segment usage diversification and in limiting potentially deleterious off-target RAG-initiated recombination events genome-wide. This review will focus mainly on studies of the mouse Ig heavy chain locus, but the principles described also apply to other Ig loci and to TCR loci in mice and humans.
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Affiliation(s)
- Sherry G Lin
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
| | - Zhaoqing Ba
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States.
| | - Yu Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
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91
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Abstract
Members of the transient receptor potential (TRP) ion channels conduct cations into cells. They mediate functions ranging from neuronally mediated hot and cold sensation to intracellular organellar and primary ciliary signaling. Here we report a cryo-electron microscopy (cryo-EM) structure of TRPC4 in its unliganded (apo) state to an overall resolution of 3.3 Å. The structure reveals a unique architecture with a long pore loop stabilized by a disulfide bond. Beyond the shared tetrameric six-transmembrane fold, the TRPC4 structure deviates from other TRP channels with a unique cytosolic domain. This unique cytosolic N-terminal domain forms extensive aromatic contacts with the TRP and the C-terminal domains. The comparison of our structure with other known TRP structures provides molecular insights into TRPC4 ion selectivity and extends our knowledge of the diversity and evolution of the TRP channels.
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92
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Abstract
The mechanism for initiating DNA cleavage by DDE-family enzymes, including the RAG endonuclease, which initiates V(D)J recombination, is not well understood. Here we report six cryo-EM structures of zebrafish RAG in complex with one or two intact recombination signal sequences (RSSs), at up to 3.9-Å resolution. Unexpectedly, these structures reveal DNA melting at the heptamer of the RSSs, thus resulting in a corkscrew-like rotation of coding-flank DNA and the positioning of the scissile phosphate in the active site. Substrate binding is associated with dimer opening and a piston-like movement in RAG1, first outward to accommodate unmelted DNA and then inward to wedge melted DNA. These precleavage complexes show limited base-specific contacts of RAG at the conserved terminal CAC/GTG sequence of the heptamer, thus suggesting conservation based on a propensity to unwind. CA and TG overwhelmingly dominate terminal sequences in transposons and retrotransposons, thereby implicating a universal mechanism for DNA melting during the initiation of retroviral integration and DNA transposition.
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93
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The RAG-2 Inhibitory Domain Gates Accessibility of the V(D)J Recombinase to Chromatin. Mol Cell Biol 2018; 38:MCB.00159-18. [PMID: 29760281 DOI: 10.1128/mcb.00159-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/01/2018] [Indexed: 02/06/2023] Open
Abstract
Accessibility of antigen receptor loci to RAG is correlated with the presence of H3K4me3, which binds to a plant homeodomain (PHD) in the RAG-2 subunit and promotes V(D)J recombination. A point mutation in the PHD, W453A, eliminates binding of H3K4me3 and impairs recombination. The debilitating effect of the W453A mutation is ameliorated by second-site mutations that locate an inhibitory domain in the interval from residues 352 through 405 of RAG-2. Disruption of the inhibitory domain stimulates V(D)J recombination within extrachromosomal substrates and at endogenous antigen receptor loci. Association of RAG-1 and RAG-2 with chromatin at the IgH locus in B cell progenitors is dependent on recognition of H3K4me3 by the PHD. Strikingly, disruption of the inhibitory domain permits association of RAG with the IgH locus in the absence of H3K4me3 binding. Thus, the inhibitory domain acts as a gate that prohibits RAG from accessing the IgH locus unless RAG-2 is engaged by H3K4me3.
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94
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Fan C, Fan M, Orlando BJ, Fastman NM, Zhang J, Xu Y, Chambers MG, Xu X, Perry K, Liao M, Feng L. X-ray and cryo-EM structures of the mitochondrial calcium uniporter. Nature 2018; 559:575-579. [PMID: 29995856 DOI: 10.1038/s41586-018-0330-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 05/17/2018] [Indexed: 01/01/2023]
Abstract
Mitochondrial calcium uptake is critical for regulating ATP production, intracellular calcium signalling, and cell death. This uptake is mediated by a highly selective calcium channel called the mitochondrial calcium uniporter (MCU). Here, we determined the structures of the pore-forming MCU proteins from two fungi by X-ray crystallography and single-particle cryo-electron microscopy. The stoichiometry, overall architecture, and individual subunit structure differed markedly from those described in the recent nuclear magnetic resonance structure of Caenorhabditis elegans MCU. We observed a dimer-of-dimer architecture across species and chemical environments, which was corroborated by biochemical experiments. Structural analyses and functional characterization uncovered the roles of key residues in the pore. These results reveal a new ion channel architecture, provide insights into calcium coordination, selectivity and conduction, and establish a structural framework for understanding the mechanism of mitochondrial calcium uniporter function.
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Affiliation(s)
- Chao Fan
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Minrui Fan
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Nathan M Fastman
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Biophysics Program, Stanford University, Stanford, CA, USA
| | - Jinru Zhang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yan Xu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Xiaofang Xu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Kay Perry
- NE-CAT and Dept. of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
| | - Liang Feng
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA. .,Biophysics Program, Stanford University, Stanford, CA, USA.
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95
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Xiao Y, Luo M, Dolan AE, Liao M, Ke A. Structure basis for RNA-guided DNA degradation by Cascade and Cas3. Science 2018; 361:eaat0839. [PMID: 29880725 PMCID: PMC6537108 DOI: 10.1126/science.aat0839] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/22/2018] [Indexed: 12/27/2022]
Abstract
Type I CRISPR-Cas system features a sequential target-searching and degradation process on double-stranded DNA by the RNA-guided Cascade (CRISPR associated complex for antiviral defense) complex and the nuclease-helicase fusion enzyme Cas3, respectively. Here, we present a 3.7-angstrom-resolution cryo-electron microscopy (cryo-EM) structure of the Type I-E Cascade/R-loop/Cas3 complex, poised to initiate DNA degradation. Cas3 distinguishes Cascade conformations and only captures the R-loop-forming Cascade, to avoid cleaving partially complementary targets. Its nuclease domain recruits the nontarget strand (NTS) DNA at a bulged region for the nicking of single-stranded DNA. An additional 4.7-angstrom-resolution cryo-EM structure captures the postnicking state, in which the severed NTS retracts to the helicase entrance, to be threaded for adenosine 5'-triphosphate-dependent processive degradation. These snapshots form the basis for understanding RNA-guided DNA degradation in Type I-E CRISPR-Cas systems.
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Affiliation(s)
- Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Min Luo
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA
| | - Adam E Dolan
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA.
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
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96
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Jain S, Ba Z, Zhang Y, Dai HQ, Alt FW. CTCF-Binding Elements Mediate Accessibility of RAG Substrates During Chromatin Scanning. Cell 2018; 174:102-116.e14. [PMID: 29804837 PMCID: PMC6026039 DOI: 10.1016/j.cell.2018.04.035] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/07/2018] [Accepted: 04/25/2018] [Indexed: 01/06/2023]
Abstract
RAG endonuclease initiates antibody heavy chain variable region exon assembly from V, D, and J segments within a chromosomal V(D)J recombination center (RC) by cleaving between paired gene segments and flanking recombination signal sequences (RSSs). The IGCR1 control region promotes DJH intermediate formation by isolating Ds, JHs, and RCs from upstream VHs in a chromatin loop anchored by CTCF-binding elements (CBEs). How VHs access the DJHRC for VH to DJH rearrangement was unknown. We report that CBEs immediately downstream of frequently rearranged VH-RSSs increase recombination potential of their associated VH far beyond that provided by RSSs alone. This CBE activity becomes particularly striking upon IGCR1 inactivation, which allows RAG, likely via loop extrusion, to linearly scan chromatin far upstream. VH-associated CBEs stabilize interactions of D-proximal VHs first encountered by the DJHRC during linear RAG scanning and thereby promote dominant rearrangement of these VHs by an unanticipated chromatin accessibility-enhancing CBE function.
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MESH Headings
- Animals
- CCCTC-Binding Factor/metabolism
- Cell Line
- Chromatin/metabolism
- DNA, Intergenic/genetics
- DNA, Intergenic/metabolism
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- Homeodomain Proteins/metabolism
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/metabolism
- Immunoglobulin Variable Region/genetics
- Immunoglobulin Variable Region/metabolism
- Mice
- Mice, Inbred C57BL
- Models, Molecular
- Mutagenesis
- Protein Sorting Signals
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- V(D)J Recombination
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Suvi Jain
- Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Zhaoqing Ba
- Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yu Zhang
- Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Hai-Qiang Dai
- Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Frederick W Alt
- Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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97
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Srivastava AP, Luo M, Zhou W, Symersky J, Bai D, Chambers MG, Faraldo-Gómez JD, Liao M, Mueller DM. High-resolution cryo-EM analysis of the yeast ATP synthase in a lipid membrane. Science 2018; 360:eaas9699. [PMID: 29650704 PMCID: PMC5948177 DOI: 10.1126/science.aas9699] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/30/2018] [Indexed: 01/06/2023]
Abstract
Mitochondrial adenosine triphosphate (ATP) synthase comprises a membrane embedded Fo motor that rotates to drive ATP synthesis in the F1 subunit. We used single-particle cryo-electron microscopy (cryo-EM) to obtain structures of the full complex in a lipid bilayer in the absence or presence of the inhibitor oligomycin at 3.6- and 3.8-angstrom resolution, respectively. To limit conformational heterogeneity, we locked the rotor in a single conformation by fusing the F6 subunit of the stator with the δ subunit of the rotor. Assembly of the enzyme with the F6-δ fusion caused a twisting of the rotor and a 9° rotation of the Fo c10-ring in the direction of ATP synthesis, relative to the structure of isolated Fo Our cryo-EM structures show how F1 and Fo are coupled, give insight into the proton translocation pathway, and show how oligomycin blocks ATP synthesis.
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Affiliation(s)
- Anurag P Srivastava
- Department of Biological Chemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Min Luo
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA
| | - Wenchang Zhou
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Bethesda, MD 20892, USA
| | - Jindrich Symersky
- Department of Biological Chemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Dongyang Bai
- Department of Biological Chemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Melissa G Chambers
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Bethesda, MD 20892, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA.
| | - David M Mueller
- Department of Biological Chemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL 60064, USA.
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98
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Kim MS, Chuenchor W, Chen X, Cui Y, Zhang X, Zhou ZH, Gellert M, Yang W. Cracking the DNA Code for V(D)J Recombination. Mol Cell 2018; 70:358-370.e4. [PMID: 29628308 DOI: 10.1016/j.molcel.2018.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 02/25/2018] [Accepted: 03/02/2018] [Indexed: 01/18/2023]
Abstract
To initiate V(D)J recombination for generating the adaptive immune response of vertebrates, RAG1/2 recombinase cleaves DNA at a pair of recombination signal sequences, the 12- and 23-RSS. We have determined crystal and cryo-EM structures of RAG1/2 with DNA in the pre-reaction and hairpin-forming complexes up to 2.75 Å resolution. Both protein and DNA exhibit structural plasticity and undergo dramatic conformational changes. Coding-flank DNAs extensively rotate, shift, and deform for nicking and hairpin formation. Two intertwined RAG1 subunits crisscross four times between the asymmetric pair of severely bent 12/23-RSS DNAs. Location-sensitive bending of 60° and 150° in 12- and 23-RSS spacers, respectively, must occur for RAG1/2 to capture the nonamers and pair the heptamers for symmetric double-strand breakage. DNA pairing is thus sequence-context dependent and structure specific, which partly explains the "beyond 12/23" restriction. Finally, catalysis in crystallo reveals the process of DNA hairpin formation and its stabilization by interleaved base stacking.
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Affiliation(s)
- Min-Sung Kim
- Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA; Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | | | - Xuemin Chen
- Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA
| | - Yanxiang Cui
- The California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Xing Zhang
- The California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA; Center of Cryo Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Z Hong Zhou
- The California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Martin Gellert
- Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
| | - Wei Yang
- Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
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99
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Vigolo M, Chambers MG, Willen L, Chevalley D, Maskos K, Lammens A, Tardivel A, Das D, Kowalczyk-Quintas C, Schuepbach-Mallepell S, Smulski CR, Eslami M, Rolink A, Hummler E, Samy E, Fomekong Nanfack Y, Mackay F, Liao M, Hess H, Jiang X, Schneider P. A loop region of BAFF controls B cell survival and regulates recognition by different inhibitors. Nat Commun 2018; 9:1199. [PMID: 29572442 PMCID: PMC5865128 DOI: 10.1038/s41467-018-03323-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 02/05/2018] [Indexed: 01/11/2023] Open
Abstract
The B cell survival factor (TNFSF13B/BAFF) is often elevated in autoimmune diseases and is targeted in the clinic for the treatment of systemic lupus erythematosus. BAFF contains a loop region designated the flap, which is dispensable for receptor binding. Here we show that the flap of BAFF has two functions. In addition to facilitating the formation of a highly active BAFF 60-mer as shown previously, it also converts binding of BAFF to TNFRSF13C (BAFFR) into a signaling event via oligomerization of individual BAFF-BAFFR complexes. Binding and activation of BAFFR can therefore be targeted independently to inhibit or activate the function of BAFF. Moreover, structural analyses suggest that the flap of BAFF 60-mer temporarily prevents binding of an anti-BAFF antibody (belimumab) but not of a decoy receptor (atacicept). The observed differences in profiles of BAFF inhibition may confer distinct biological and clinical efficacies to these therapeutically relevant inhibitors. BAFF is an important cytokine for B cell survival, and is a therapeutic target for autoimmune disorders. Here the authors show that a 'flap' region of BAFF converts BAFFR binding events into survival signals and, with structural data, that this ‘flap’ differentially modulates binding of drugs such as belimumab or atacicept.
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Affiliation(s)
- Michele Vigolo
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Melissa G Chambers
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Laure Willen
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Dehlia Chevalley
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Klaus Maskos
- Proteros Biostructures GmbH, 82152, Planegg, Germany
| | | | - Aubry Tardivel
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Dolon Das
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | | | | | - Cristian R Smulski
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Mahya Eslami
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland
| | - Antonius Rolink
- Department of Biomedicine, University of Basel, 4058, Basel, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, 1011, Lausanne, Switzerland
| | - Eileen Samy
- EMD Serono Research & Development Institute, Billerica, MA, 01821, USA
| | | | - Fabienne Mackay
- Department of Immunology, Monash University, Melbourne, VIC, 3004, Australia
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | | | - Xuliang Jiang
- EMD Serono Research & Development Institute, Billerica, MA, 01821, USA
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland.
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100
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Popp D, Koh F, Scipion CPM, Ghoshdastider U, Narita A, Holmes KC, Robinson RC. Advances in Structural Biology and the Application to Biological Filament Systems. Bioessays 2018; 40:e1700213. [PMID: 29484695 DOI: 10.1002/bies.201700213] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/10/2018] [Indexed: 11/10/2022]
Abstract
Structural biology has experienced several transformative technological advances in recent years. These include: development of extremely bright X-ray sources (microfocus synchrotron beamlines and free electron lasers) and the use of electrons to extend protein crystallography to ever decreasing crystal sizes; and an increase in the resolution attainable by cryo-electron microscopy. Here we discuss the use of these techniques in general terms and highlight their application for biological filament systems, an area that is severely underrepresented in atomic resolution structures. We assemble a model of a capped tropomyosin-actin minifilament to demonstrate the utility of combining structures determined by different techniques. Finally, we survey the methods that attempt to transform high resolution structural biology into more physiological environments, such as the cell. Together these techniques promise a compelling decade for structural biology and, more importantly, they will provide exciting discoveries in understanding the designs and purposes of biological machines.
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Affiliation(s)
- David Popp
- Institute of Molecular and Cell Biology A*STAR (Agency for Science, Technology and Research) Biopolis, Singapore 138673, Singapore
| | - Fujiet Koh
- Institute of Molecular and Cell Biology A*STAR (Agency for Science, Technology and Research) Biopolis, Singapore 138673, Singapore
| | - Clement P M Scipion
- Institute of Molecular and Cell Biology A*STAR (Agency for Science, Technology and Research) Biopolis, Singapore 138673, Singapore.,Department of Biochemistry Yong Loo Lin School of Medicine National University of Singapore, Singapore 117597, Singapore
| | - Umesh Ghoshdastider
- Institute of Molecular and Cell Biology A*STAR (Agency for Science, Technology and Research) Biopolis, Singapore 138673, Singapore
| | - Akihiro Narita
- Nagoya University Graduate School of Science Structural Biology Research Center and Division of Biological Sciences, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Kenneth C Holmes
- Max Planck Institute for Medical Research, D69120 Heidelberg, Germany
| | - Robert C Robinson
- Institute of Molecular and Cell Biology A*STAR (Agency for Science, Technology and Research) Biopolis, Singapore 138673, Singapore.,Department of Biochemistry Yong Loo Lin School of Medicine National University of Singapore, Singapore 117597, Singapore.,Research Institute for Interdisciplinary Science Okayama University, Okayama 700-8530, Japan
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