1
|
Guo ZJ, Liang HX, Lian XY, Liao XJ, Xing XW, Xu SH, Zhao BX. (+)- and (-)-Tedanine, a pair of new enantiomeric indolone alkaloids from the marine sponge Tedania sp. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2024; 26:328-333. [PMID: 37602427 DOI: 10.1080/10286020.2023.2244432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 08/22/2023]
Abstract
(+)- and (-)-Tedanine [(+)-1 and (-)-1], a pair of new enantiomeric indolone alkaloids, along with nine compounds (2-10) were isolated from the marine sponge Tedania sp. The structures of (+)-1 and (-)-1 including absolute configurations were determined by spectroscopic analysis and quantum chemical calculation. Compounds (+)-1 and (-)-1 were the first examples of indolone alkaloids isolated from this genus. In addition, the cytotoxic and antibacterial activities of these compounds were also evaluated.
Collapse
Affiliation(s)
- Ze-Jie Guo
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Hui-Xian Liang
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Xiao-Ying Lian
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Xiao-Jian Liao
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Xi-Wen Xing
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Shi-Hai Xu
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| | - Bing-Xin Zhao
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China
| |
Collapse
|
2
|
Chu L, Gong Z, Wang W, Han GZ. Origin of the OAS-RNase L innate immune pathway before the rise of jawed vertebrates via molecular tinkering. Proc Natl Acad Sci U S A 2023; 120:e2304687120. [PMID: 37487089 PMCID: PMC10400998 DOI: 10.1073/pnas.2304687120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/26/2023] [Indexed: 07/26/2023] Open
Abstract
Discriminating self from nonself is fundamental to immunity. Yet, it remains largely elusive how the mechanisms of self and nonself discrimination originated. Sensing double-stranded RNA as nonself, the 2',5'-oligoadenylate synthetase (OAS)-ribonuclease L (RNase L) pathway represents a crucial component of innate immunity. Here, we combine phylogenomic and functional analyses to show that the functional OAS-RNase L pathway likely originated through tinkering with preexisting proteins before the rise of jawed vertebrates during or before the Silurian period (444 to 419 Mya). Multiple concerted losses of OAS and RNase L occurred during the evolution of jawed vertebrates, further supporting the ancient coupling between OAS and RNase L. Moreover, both OAS and RNase L genes evolved under episodic positive selection across jawed vertebrates, suggesting a long-running evolutionary arms race between the OAS-RNase L pathway and microbes. Our findings illuminate how an innate immune pathway originated via molecular tinkering.
Collapse
Affiliation(s)
- Lingyu Chu
- College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu210023, China
| | - Zhen Gong
- College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu210023, China
| | - Wenqiang Wang
- College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu210023, China
| | - Guan-Zhu Han
- College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu210023, China
| |
Collapse
|
3
|
Wang X, Hu J, Song L, Rong E, Yang C, Chen X, Pu J, Sun H, Gao C, Burt DW, Liu J, Li N, Huang Y. Functional divergence of oligoadenylate synthetase 1 (OAS1) proteins in Tetrapods. SCIENCE CHINA. LIFE SCIENCES 2022; 65:1395-1412. [PMID: 34826092 DOI: 10.1007/s11427-021-2002-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
OASs play critical roles in immune response against virus infection by polymerizing ATP into 2-5As, which initiate the classical OAS/RNase L pathway and induce degradation of viral RNA. OAS members are functionally diverged in four known innate immune pathways (OAS/RNase L, OASL/IRF7, OASL/RIG-I, and OASL/cGAS), but how they functionally diverged is unclear. Here, we focus on evolutionary patterns and explore the link between evolutionary processes and functional divergence of Tetrapod OAS1. We show that Palaeognathae and Primate OAS1 genes are conserved in genomic and protein structures but differ in function. The former (i.e., ostrich) efficiently synthesized long 2-5A and activated RNase L, while the latter (i.e., human) synthesized short 2-5A and did not activate RNase L. We predicted and verified that two in-frame indels and one positively selected site in the active site pocket contributed to the functional divergence of Palaeognathae and Primate OAS1. Moreover, we discovered and validated that an in-frame indel in the C-terminus of Palaeognathae OAS1 affected the binding affinity of dsRNA and enzymatic activity, and contributed to the functional divergence of Palaeognathae OAS1 proteins. Our findings unravel the molecular mechanism for functional divergence and give insights into the emergence of novel functions in Tetrapod OAS1.
Collapse
Affiliation(s)
- Xiaoxue Wang
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - Jiaxiang Hu
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - Linfei Song
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - Enguang Rong
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - Chenghuai Yang
- China Institute of Veterinary Drug Control, Beijing, 100081, China
| | - Xiaoyun Chen
- China Institute of Veterinary Drug Control, Beijing, 100081, China
| | - Juan Pu
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100083, China
| | - Honglei Sun
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100083, China
| | - Chuze Gao
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - David W Burt
- University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia
| | - Jinhua Liu
- Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100083, China
| | - Ning Li
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China
| | - Yinhua Huang
- State Key Laboratory for Agrobiotechnology, College of Biology Sciences, China Agricultural University, Beijing, 100193, China.
| |
Collapse
|
4
|
RNA-seq of HaHV-1-infected abalones reveals a common transcriptional signature of Malacoherpesviruses. Sci Rep 2019; 9:938. [PMID: 30700734 PMCID: PMC6353905 DOI: 10.1038/s41598-018-36433-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/31/2018] [Indexed: 12/21/2022] Open
Abstract
Haliotid herpesvirus-1 (HaHV-1) is the viral agent causative of abalone viral ganglioneuritis, a disease that has severely affected gastropod aquaculture. Although limited, the sequence similarity between HaHV-1 and Ostreid herpesvirus-1 supported the assignment of both viruses to Malacoherpesviridae, a Herpesvirales family distantly related with other viruses. In this study, we reported the first transcriptional data of HaHV-1, obtained from an experimental infection of Haliotis diversicolor supertexta. We also sequenced the genome draft of the Chinese HaHV-1 variant isolated in 2003 (HaHV-1-CN2003) by PacBio technology. Analysis of 13 million reads obtained from 3 RNA samples at 60 hours post injection (hpi) allowed the prediction of 51 new ORFs for a total of 117 viral genes and the identification of 207 variations from the reference genome, consisting in 135 Single Nucleotide Polymorphisms (SNPs) and 72 Insertions or Deletions (InDels). The pairing of genomic and transcriptomic data supported the identification of 60 additional SNPs, representing viral transcriptional variability and preferentially grouped in hotspots. The expression analysis of HaHV-1 ORFs revealed one putative secreted protein, two putative capsid proteins and a possible viral capsid protease as the most expressed genes and demonstrated highly synchronized viral expression patterns of the 3 infected animals at 60 hpi. Quantitative reverse transcription data of 37 viral genes supported the burst of viral transcription at 30 and 60 hpi during the 72 hours of the infection experiment, and allowed the distinction between early and late viral genes.
Collapse
|
5
|
Evolutionary distribution of deoxynucleoside 5-monophosphate N-glycosidase, DNPH1. Gene 2019; 683:1-11. [DOI: 10.1016/j.gene.2018.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 09/10/2018] [Accepted: 10/03/2018] [Indexed: 01/01/2023]
|
6
|
Hu J, Wang X, Xing Y, Rong E, Ning M, Smith J, Huang Y. Origin and development of oligoadenylate synthetase immune system. BMC Evol Biol 2018; 18:201. [PMID: 30587119 PMCID: PMC6307210 DOI: 10.1186/s12862-018-1315-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/04/2018] [Indexed: 12/19/2022] Open
Abstract
Background Oligoadenylate synthetases (OASs) are widely distributed in Metazoa including sponges, fish, reptiles, birds and mammals and show large variation, with one to twelve members in any given species. Upon double-stranded RNA (dsRNA) binding, avian and mammalian OASs generate the second messenger 2'-5'-linked oligoadenylate (2-5A), which activates ribonuclease L (RNaseL) and blocks viral replication. However, how Metazoa shape their OAS repertoires to keep evolutionary balance to virus infection is largely unknown. We performed comprehensive phylogenetic and functional analyses of OAS genes from evolutionarily lower to higher Metazoa to demonstrate how the OAS repertoires have developed anti-viral activity and diversified their functions. Results Ancient Metazoa harbor OAS genes, but lack both upstream and downstream genes of the OAS-related pathways, indicating that ancient OASs are not interferon-induced genes involved in the innate immune system. Compared to OASs of ancient Metazoa (i.e. sponge), the corresponding ones of higher Metazoa present an increasing number of basic residues on the OAS/dsRNA interaction interface. Such an increase of basic residues might improve their binding affinity to dsRNA. Moreover, mutations of functional residues in the active pocket might lead to the fact that higher Metazoan OASs lose the ability to produce 3'-5'-linked oligoadenylate (3-5A) and turn into specific 2-5A synthetases. In addition, we found that multiple rounds of gene duplication and domain coupling events occurred in the OAS family and mutations at functionally critical sites were observed in most new OAS members. Conclusions We propose a model for the expansion of OAS members and provide comprehensive evidence of subsequent neo-functionalization and sub-functionalization. Our observations lay the foundation for interrogating the evolutionary transition of ancient OAS genes to host defense genes and provide important information for exploring the unknown function of the OAS gene family. Electronic supplementary material The online version of this article (10.1186/s12862-018-1315-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jiaxiang Hu
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China
| | - Xiaoxue Wang
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China
| | - Yanling Xing
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China
| | - Enguang Rong
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China
| | - Mengfei Ning
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China
| | - Jacqueline Smith
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Yinhua Huang
- State Key Laboratory for Agrobiotechnology, China Agricultural University, No.2 Yuan Ming Yuan West Road, Hai Dian District, Beijing, 100193, China.
| |
Collapse
|
7
|
Lopp A, Reintamm T, Kuusksalu A, Olspert A, Kelve M. Identification of a novel member of 2H phosphoesterases, 2',5'-oligoadenylate degrading ribonuclease from the oyster Crassostrea gigas. Biochimie 2018; 156:181-195. [PMID: 30195052 DOI: 10.1016/j.biochi.2018.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/03/2018] [Indexed: 11/16/2022]
Abstract
Several genes of IFN-mediated pathways in vertebrates, among them the genes that participate in the 2',5'-oligoadenylate synthetase (OAS)/RNase L pathway, have been identified in C. gigas. In the present study, we identified genes, which encode proteins having 2',5'-oligoadenylate degrading activity in C. gigas. These proteins belong to the 2H phosphoesterase superfamily and have sequence similarity to the mammalian A kinase anchoring protein 7 (AKAP7) central domain, which is responsible for the 2',5'-phosphodiesterase (2',5'-PDE) activity. Comparison of the genomic structures of C. gigas proteins with that of AKAP7 suggests that these enzymes originate from a direct common ancestor. However, the identified nucleases are not typical 2',5'-PDEs. The found enzymes catalyse the degradation of 2',5'-linked oligoadenylates in a metal-ion-independent way, yielding products with 2',3' -cyclic phosphate and 5'-OH termini similarly to the 3'-5' bond cleavage in RNA, catalyzed by metal-independent ribonucleases. 3',5'-linked oligoadenylates are not substrates for them. The preferred substrates for the C. gigas enzymes are 5'-triphosphorylated 2',5'-oligoadenylates, whose major cleavage reaction results in the removal of the 5'-triphosphorylated 2',3'-cyclic phosphate derivative, leaving behind the respective unphosphorylated 2',5'-oligoadenylate. Such a cleavage reaction results in the direct inactivation of the biologically active 2-5A molecule. The 2',5'-ribonucleases (2',5'-RNases) from C. gigas could be members of the ancient group of ribonucleases, specific to 2'-5' phosphodiester bond, together with the enzyme that was characterized previously from the marine sponge Tethya aurantium. The novel 2',5'-RNases may play a role in the control of cellular 2-5A levels, thereby limiting damage to host cells after viral infection.
Collapse
Affiliation(s)
- Annika Lopp
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Akadeemia Tee 15, Tallinn, 12618, Estonia.
| | - Tõnu Reintamm
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Akadeemia Tee 15, Tallinn, 12618, Estonia
| | - Anne Kuusksalu
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Akadeemia Tee 15, Tallinn, 12618, Estonia
| | - Allan Olspert
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Akadeemia Tee 15, Tallinn, 12618, Estonia
| | - Merike Kelve
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Akadeemia Tee 15, Tallinn, 12618, Estonia
| |
Collapse
|
8
|
Paces J, Nic M, Novotny T, Svoboda P. Literature review of baseline information to support the risk assessment of RNAi‐based GM plants. ACTA ACUST UNITED AC 2017. [PMCID: PMC7163844 DOI: 10.2903/sp.efsa.2017.en-1246] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jan Paces
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
| | | | | | - Petr Svoboda
- Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic (IMG)
| |
Collapse
|
9
|
Poulsen JB, Kjær KH, Justesen J, Martensen PM. Enzyme assays for synthesis and degradation of 2-5As and other 2'-5' oligonucleotides. BMC BIOCHEMISTRY 2015; 16:15. [PMID: 26113370 PMCID: PMC4481073 DOI: 10.1186/s12858-015-0043-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/15/2015] [Indexed: 01/12/2023]
Abstract
Background The 5′-triphosphorylated, 2′-5′-linked oligoadenylate polyribonucleotides (2-5As) are central to the interferon-induced antiviral 2-5A system. The 2-5As bind and activate the RNase L, an endoRNase degrading viral and cellular RNA leading to inhibition of viral replication. The 2-5A system is tightly controlled by synthesis and degradation of 2-5As. Whereas synthesis is mediated by the 2′-5′ oligoadenylate synthetase family of enzymes, degradation seems to be orchestrated by multiple enzyme nucleases including phosphodiesterase 12, the ectonucleotide pyrophosphatase/phosphodiesterase 1 and the A-kinase anchoring protein 7. Results Here we present assay tools for identification and characterization of the enzymes regulating cellular 2-5A levels. A procedure is described for the production of 2′-5′ oligoadenylates, which are then used as substrates for development and demonstration of enzyme assays measuring synthetase and nuclease activities, respectively. The synthetase assays produce only a single reaction product allowing for very precise kinetic assessment of the enzymes. We present an assay using dATP and the A(pA)3 tetramer core as substrates, which requires prior isolation of A(pA)3. A synthetase assay using either of the dNTPs individually together with NAD+ as substrates is also presented. The nuclease reactions make use of the isolated 2′-5′ oligoadenylates in producing a mixture of shorter reaction products, which are resolved by ion-exchange chromatography to determine the enzyme activities. A purified human 2′-5′ oligoadenylate synthetase and a purified human phosphodiesterase 12 along with crude extracts expressing those proteins, are used to demonstrate the assays. Conclusions This paper comprises an assay toolbox for identification and characterization of the synthetases and nucleases regulating cellular 2-5A levels. Assays are presented for both enzyme families. The assays can also be used to address a broader cellular role of the OAS enzymes, based on the multiple substrate specificity intrinsic to these proteins. Electronic supplementary material The online version of this article (doi:10.1186/s12858-015-0043-8) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jesper Buchhave Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| | - Karina Hansen Kjær
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| | - Just Justesen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| | - Pia Møller Martensen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| |
Collapse
|
10
|
Zhu J, Ghosh A, Sarkar SN. OASL-a new player in controlling antiviral innate immunity. Curr Opin Virol 2015; 12:15-9. [PMID: 25676874 DOI: 10.1016/j.coviro.2015.01.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/17/2015] [Accepted: 01/22/2015] [Indexed: 01/17/2023]
Abstract
The cellular innate immune system plays a crucial role in mounting the initial resistance to virus infection. It is comprised of various pattern-recognition receptors that induce type I interferon production, which further shapes the adaptive immunity. However, to overcome this resistance and promote replication, viruses have evolved mechanisms to evade this host innate immune response. Here we discuss a recently described mechanism of boosting the innate immunity by oligoadenylate synthetase-like (OASL) protein, which can potentially be used to overcome viral evasion and enhance innate immunity.
Collapse
Affiliation(s)
- Jianzhong Zhu
- Cancer Virology Program, University of Pittsburgh Cancer Institute, United States; Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Arundhati Ghosh
- Cancer Virology Program, University of Pittsburgh Cancer Institute, United States; Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Saumendra N Sarkar
- Cancer Virology Program, University of Pittsburgh Cancer Institute, United States; Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
| |
Collapse
|
11
|
Strand-specific (asymmetric) contribution of phosphodiester linkages on RNA polymerase II transcriptional efficiency and fidelity. Proc Natl Acad Sci U S A 2014; 111:E3269-76. [PMID: 25074911 DOI: 10.1073/pnas.1406234111] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Nonenzymatic RNA polymerization in early life is likely to introduce backbone heterogeneity with a mixture of 2'-5' and 3'-5' linkages. On the other hand, modern nucleic acids are dominantly composed of 3'-5' linkages. RNA polymerase II (pol II) is a key modern enzyme responsible for synthesizing 3'-5'-linked RNA with high fidelity. It is not clear how modern enzymes, such as pol II, selectively recognize 3'-5' linkages over 2'-5' linkages of nucleic acids. In this work, we systematically investigated how phosphodiester linkages of nucleic acids govern pol II transcriptional efficiency and fidelity. Through dissecting the impacts of 2'-5' linkage mutants in the pol II catalytic site, we revealed that the presence of 2'-5' linkage in RNA primer only modestly reduces pol II transcriptional efficiency without affecting pol II transcriptional fidelity. In sharp contrast, the presence of 2'-5' linkage in DNA template leads to dramatic decreases in both transcriptional efficiency and fidelity. These distinct effects reveal that pol II has an asymmetric (strand-specific) recognition of phosphodiester linkage. Our results provided important insights into pol II transcriptional fidelity, suggesting essential contributions of phosphodiester linkage to pol II transcription. Finally, our results also provided important understanding on the molecular basis of nucleic acid recognition and genetic information transfer during molecular evolution. We suggest that the asymmetric recognition of phosphodiester linkage by modern nucleic acid enzymes likely stems from the distinct evolutionary pressures of template and primer strand in genetic information transfer during molecular evolution.
Collapse
|
12
|
OAS proteins and cGAS: unifying concepts in sensing and responding to cytosolic nucleic acids. Nat Rev Immunol 2014; 14:521-8. [PMID: 25033909 PMCID: PMC7097587 DOI: 10.1038/nri3719] [Citation(s) in RCA: 211] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The presence of nucleic acids in the cytosol alerts the cell to viral infection or damaged self. The oligoadenylate synthase (OAS) proteins and cyclic GMP–AMP synthase (cGAS) are enzymes that detect this danger and promote antiviral immunity. Recent structural studies reveal that these enzymes have a common mechanism of action and probably the same evolutionary origin. Recent discoveries in the field of innate immunity have highlighted the existence of a family of nucleic acid-sensing proteins that have similar structural and functional properties. These include the well-known oligoadenylate synthase (OAS) family proteins and the recently identified OAS homologue cyclic GMP–AMP (cGAMP) synthase (cGAS). The OAS proteins and cGAS are template-independent nucleotidyltransferases that, once activated by double-stranded nucleic acids in the cytosol, produce unique classes of 2′–5′-linked second messenger molecules, which — through distinct mechanisms — have crucial antiviral functions. 2′–5′-linked oligoadenylates limit viral propagation through the activation of the enzyme RNase L, which degrades host and viral RNA, and 2′–5′-linked cGAMP activates downstream signalling pathways to induce de novo antiviral gene expression. In this Progress article, we describe the striking functional and structural similarities between OAS proteins and cGAS, and highlight their roles in antiviral immunity.
Collapse
|