1
|
Monette A, Mouland AJ. Zinc and Copper Ions Differentially Regulate Prion-Like Phase Separation Dynamics of Pan-Virus Nucleocapsid Biomolecular Condensates. Viruses 2020; 12:E1179. [PMID: 33081049 PMCID: PMC7589941 DOI: 10.3390/v12101179] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/05/2020] [Accepted: 10/12/2020] [Indexed: 02/08/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) is a rapidly growing research focus due to numerous demonstrations that many cellular proteins phase-separate to form biomolecular condensates (BMCs) that nucleate membraneless organelles (MLOs). A growing repertoire of mechanisms supporting BMC formation, composition, dynamics, and functions are becoming elucidated. BMCs are now appreciated as required for several steps of gene regulation, while their deregulation promotes pathological aggregates, such as stress granules (SGs) and insoluble irreversible plaques that are hallmarks of neurodegenerative diseases. Treatment of BMC-related diseases will greatly benefit from identification of therapeutics preventing pathological aggregates while sparing BMCs required for cellular functions. Numerous viruses that block SG assembly also utilize or engineer BMCs for their replication. While BMC formation first depends on prion-like disordered protein domains (PrLDs), metal ion-controlled RNA-binding domains (RBDs) also orchestrate their formation. Virus replication and viral genomic RNA (vRNA) packaging dynamics involving nucleocapsid (NC) proteins and their orthologs rely on Zinc (Zn) availability, while virus morphology and infectivity are negatively influenced by excess Copper (Cu). While virus infections modify physiological metal homeostasis towards an increased copper to zinc ratio (Cu/Zn), how and why they do this remains elusive. Following our recent finding that pan-retroviruses employ Zn for NC-mediated LLPS for virus assembly, we present a pan-virus bioinformatics and literature meta-analysis study identifying metal-based mechanisms linking virus-induced BMCs to neurodegenerative disease processes. We discover that conserved degree and placement of PrLDs juxtaposing metal-regulated RBDs are associated with disease-causing prion-like proteins and are common features of viral proteins responsible for virus capsid assembly and structure. Virus infections both modulate gene expression of metalloproteins and interfere with metal homeostasis, representing an additional virus strategy impeding physiological and cellular antiviral responses. Our analyses reveal that metal-coordinated virus NC protein PrLDs initiate LLPS that nucleate pan-virus assembly and contribute to their persistence as cell-free infectious aerosol droplets. Virus aerosol droplets and insoluble neurological disease aggregates should be eliminated by physiological or environmental metals that outcompete PrLD-bound metals. While environmental metals can control virus spreading via aerosol droplets, therapeutic interference with metals or metalloproteins represent additional attractive avenues against pan-virus infection and virus-exacerbated neurological diseases.
Collapse
Affiliation(s)
- Anne Monette
- Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada
| | - Andrew J. Mouland
- Lady Davis Institute at the Jewish General Hospital, Montréal, QC H3T 1E2, Canada
- Department of Medicine, McGill University, Montréal, QC H4A 3J1, Canada
| |
Collapse
|
2
|
Martínez-Sobrido L, Peersen O, Nogales A. Temperature Sensitive Mutations in Influenza A Viral Ribonucleoprotein Complex Responsible for the Attenuation of the Live Attenuated Influenza Vaccine. Viruses 2018; 10:E560. [PMID: 30326610 PMCID: PMC6213772 DOI: 10.3390/v10100560] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 10/03/2018] [Accepted: 10/12/2018] [Indexed: 01/29/2023] Open
Abstract
Live attenuated influenza vaccines (LAIV) have prevented morbidity and mortality associated with influenza viral infections for many years and represent the best therapeutic option to protect against influenza viral infections in humans. However, the development of LAIV has traditionally relied on empirical methods, such as the adaptation of viruses to replicate at low temperatures. These approaches require an extensive investment of time and resources before identifying potential vaccine candidates that can be safely implemented as LAIV to protect humans. In addition, the mechanism of attenuation of these vaccines is poorly understood in some cases. Importantly, LAIV are more efficacious than inactivated vaccines because their ability to mount efficient innate and adaptive humoral and cellular immune responses. Therefore, the design of potential LAIV based on known properties of viral proteins appears to be a highly appropriate option for the treatment of influenza viral infections. For that, the viral RNA synthesis machinery has been a research focus to identify key amino acid substitutions that can lead to viral attenuation and their use in safe, immunogenic, and protective LAIV. In this review, we discuss the potential to manipulate the influenza viral RNA-dependent RNA polymerase (RdRp) complex to generate attenuated forms of the virus that can be used as LAIV for the treatment of influenza viral infections, one of the current and most effective prophylactic options for the control of influenza in humans.
Collapse
Affiliation(s)
- Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, NY 14642, USA.
| | - Olve Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, CO 80523, USA.
| | - Aitor Nogales
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, NY 14642, USA.
| |
Collapse
|
3
|
Kordyukova LV, Shtykova EV, Baratova LA, Svergun DI, Batishchev OV. Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein. J Biomol Struct Dyn 2018; 37:671-690. [PMID: 29388479 DOI: 10.1080/07391102.2018.1436089] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Influenza A virus, a member of the Orthomyxoviridae family of enveloped viruses, is one of the human and animal top killers, and its structure and components are therefore extensively studied during the last decades. The most abundant component, M1 matrix protein, forms a matrix layer (scaffold) under the viral lipid envelope, and the functional roles as well as structural peculiarities of the M1 protein are still under heavy debate. Despite multiple attempts of crystallization, no high resolution structure is available for the full length M1 of Influenza A virus. The likely reason for the difficulties lies in the intrinsic disorder of the M1 C-terminal part preventing diffraction quality crystals to be grown. Alternative structural methods including synchrotron small-angle X-ray scattering (SAXS), atomic force microscopy, cryo-electron microscopy/tomography are therefore widely applied to understand the structure of M1, its self-association and interactions with the lipid membrane and the viral nucleocapsid. These methods reveal striking similarities in the behavior of M1 and matrix proteins of other enveloped RNA viruses, with the differences accompanied by the specific features of the viral lifecycles, thus suggesting common interaction principles and, possibly, common evolutional ancestors. The structural information on the Influenza A virus M1 protein obtained to the date strongly suggests that the intrinsic disorder in the C-terminal domain has important functional implications.
Collapse
Affiliation(s)
- Larisa V Kordyukova
- a Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Eleonora V Shtykova
- b Shubnikov Institute of Crystallography of Federal Scientific Research Centre 'Crystallography and Photonics' of Russian Academy of Sciences , Moscow , Russian Federation.,c Semenov Institute of Chemical Physics , Russian Academy of Sciences , Moscow , Russian Federation
| | - Lyudmila A Baratova
- a Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | | | - Oleg V Batishchev
- e Frumkin Institute of Physical Chemistry and Electrochemistry , Russian Academy of Sciences , Moscow , Russian Federation.,f Moscow Institute of Physics and Technology , Dolgoprudniy , Russian Federation
| |
Collapse
|
4
|
Khaliq Z, Leijon M, Belák S, Komorowski J. Identification of combinatorial host-specific signatures with a potential to affect host adaptation in influenza A H1N1 and H3N2 subtypes. BMC Genomics 2016; 17:529. [PMID: 27473048 PMCID: PMC4966792 DOI: 10.1186/s12864-016-2919-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 07/07/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The underlying strategies used by influenza A viruses (IAVs) to adapt to new hosts while crossing the species barrier are complex and yet to be understood completely. Several studies have been published identifying singular genomic signatures that indicate such a host switch. The complexity of the problem suggested that in addition to the singular signatures, there might be a combinatorial use of such genomic features, in nature, defining adaptation to hosts. RESULTS We used computational rule-based modeling to identify combinatorial sets of interacting amino acid (aa) residues in 12 proteins of IAVs of H1N1 and H3N2 subtypes. We built highly accurate rule-based models for each protein that could differentiate between viral aa sequences coming from avian and human hosts. We found 68 host-specific combinations of aa residues, potentially associated to host adaptation on HA, M1, M2, NP, NS1, NEP, PA, PA-X, PB1 and PB2 proteins of the H1N1 subtype and 24 on M1, M2, NEP, PB1 and PB2 proteins of the H3N2 subtypes. In addition to these combinations, we found 132 novel singular aa signatures distributed among all proteins, including the newly discovered PA-X protein, of both subtypes. We showed that HA, NA, NP, NS1, NEP, PA-X and PA proteins of the H1N1 subtype carry H1N1-specific and HA, NA, PA-X, PA, PB1-F2 and PB1 of the H3N2 subtype carry H3N2-specific signatures. M1, M2, PB1-F2, PB1 and PB2 of H1N1 subtype, in addition to H1N1 signatures, also carry H3N2 signatures. Similarly M1, M2, NP, NS1, NEP and PB2 of H3N2 subtype were shown to carry both H3N2 and H1N1 host-specific signatures (HSSs). CONCLUSIONS To sum it up, we computationally constructed simple IF-THEN rule-based models that could distinguish between aa sequences of avian and human IAVs. From the rules we identified HSSs having a potential to affect the adaptation to specific hosts. The identification of combinatorial HSSs suggests that the process of adaptation of IAVs to a new host is more complex than previously suggested. The present study provides a basis for further detailed studies with the aim to elucidate the molecular mechanisms providing the foundation for the adaptation process.
Collapse
Affiliation(s)
- Zeeshan Khaliq
- Department of Cell and Molecular Biology, Computational Biology and Bioinformatics, Science for Life Laboratory, Uppsala University, SE-751 24, Uppsala, Sweden
| | - Mikael Leijon
- Department of Virology, Parasitology and Immunobiology (VIP), National Veterinary Institute (SVA), Uppsala, Sweden.,OIE Collaborating Centre for the Biotechnology-based Diagnosis of Infectious Diseases in Veterinary Medicine, Ulls väg 2B and 26, SE-756 89, Uppsala, Sweden
| | - Sándor Belák
- OIE Collaborating Centre for the Biotechnology-based Diagnosis of Infectious Diseases in Veterinary Medicine, Ulls väg 2B and 26, SE-756 89, Uppsala, Sweden.,Department of Biomedical Sciences and Veterinary Public Health (BVF), Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Jan Komorowski
- Department of Cell and Molecular Biology, Computational Biology and Bioinformatics, Science for Life Laboratory, Uppsala University, SE-751 24, Uppsala, Sweden. .,Institute of Computer Science, Polish Academy of Sciences, 01-248, Warszawa, Poland.
| |
Collapse
|
5
|
The compensatory G88R change is essential in restoring the normal functions of influenza A/WSN/33 virus matrix protein 1 with a disrupted nuclear localization signal. J Virol 2012; 87:345-53. [PMID: 23077315 DOI: 10.1128/jvi.02024-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
G88R emerged as a compensatory mutation in matrix protein 1 (M1) of influenza virus A/WSN/33 when its nuclear localization signal (NLS) was disrupted by R101S and R105S substitutions. The resultant M1 triple mutant M(NLS-88R) regained replication efficiency in vitro while remaining attenuated in vivo with the potential of being a live vaccine candidate. To understand why G88R was favored by the virus as a compensatory change for the NLS loss and resultant replication deficiency, three more M1 triple mutants with an alternative G88K, G88V, or G88E change in addition to R101S and R105S substitutions in the NLS were generated. Unlike the other M1 triple mutants, M(NLS-88R) replicated more efficiently in vitro and in vivo. The G88R compensatory mutation not only restored normal functions of M1 in the presence of a disrupted NLS but also resulted in a strong association of M1 with viral ribonucleoprotein. Under a transmission electron microscope, only the M1 layer of the M(NLS-88R) virion exhibited discontinuous fingerprint-like patterns with average thicknesses close to that of wild-type A/WSN/33. Computational modeling suggested that the compensatory G88R change could reestablish the integrity of the M1 layer through new salt bridges between adjacent M1 subunits when the original interactions were interrupted by simultaneous R101S and R105S replacements in the NLS. Our results suggested that restoring the normal functions of M1 was crucial for efficient virus replication.
Collapse
|
6
|
The cytoplasmic tail domain of influenza B virus hemagglutinin is important for its incorporation into virions but is not essential for virus replication in cell culture in the presence of compensatory mutations. J Virol 2012; 86:11633-44. [PMID: 22896616 DOI: 10.1128/jvi.01479-12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza B virus hemagglutinin (BHA) contains a predicted cytoplasmic tail of 10 amino acids that are highly conserved among influenza B viruses. To understand the role of this cytoplasmic tail in infectious virus production, we used reverse genetics to generate a recombinant influenza B virus lacking the BHA cytoplasmic tail domain. The resulting virus, designated BHATail(-), had a titer approximately 5 log units lower than that of wild-type virus but grew normally when BHA was supplemented in trans by BHA-expressing cells. Although the levels of BHA cell surface expression were indistinguishable between truncated and wild-type BHA, the BHATail(-) virus produced particles containing dramatically less BHA. Moreover, removal of the cytoplasmic tail abrogated the association of BHA with Triton X-100-insoluble lipid rafts. Interestingly, long-term culture of a virus lacking the BHA cytoplasmic tail in Madin-Darby canine kidney (MDCK) cells yielded a mutant with infectivities somewhat similar to that of wild-type virus. Sequencing revealed that the mutant virus retained the original cytoplasmic tail deletion but acquired additional mutations in its BHA, neuraminidase (NA), and M1 proteins. Viral growth kinetic analysis showed that replication of BHA cytoplasmic tailless viruses could be improved by compensatory mutations in the NA and M1 proteins. These findings indicate that the cytoplasmic tail domain of BHA is important for efficient incorporation of BHA into virions and tight lipid raft association. They also demonstrate that the domain is not absolutely required for virus viability in cell culture in the presence of compensatory mutations.
Collapse
|
7
|
Terrier O, Moules V, Carron C, Cartet G, Frobert E, Yver M, Traversier A, Wolff T, Riteau B, Naffakh N, Lina B, Diaz JJ, Rosa-Calatrava M. The influenza fingerprints: NS1 and M1 proteins contribute to specific host cell ultrastructure signatures upon infection by different influenza A viruses. Virology 2012; 432:204-18. [PMID: 22770924 DOI: 10.1016/j.virol.2012.05.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/02/2012] [Accepted: 05/21/2012] [Indexed: 12/22/2022]
Abstract
Influenza A are nuclear replicating viruses which hijack host machineries in order to achieve optimal infection. Numerous functional virus-host interactions have now been characterized, but little information has been gathered concerning their link to the virally induced remodeling of the host cellular architecture. In this study, we infected cells with several human and avian influenza viruses and we have analyzed their ultrastructural modifications by using electron and confocal microscopy. We discovered that infections lead to a major and systematic disruption of nucleoli and the formation of a large number of diverse viral structures showing specificity that depended on the subtype origin and genomic composition of viruses. We identified NS1 and M1 proteins as the main actors in the remodeling of the host ultra-structure and our results suggest that each influenza A virus strain could be associated with a specific cellular fingerprint, possibly correlated to the functional properties of their viral components.
Collapse
Affiliation(s)
- Olivier Terrier
- Equipe VirCell, Laboratoire de Virologie et Pathologie Humaine, VirPath EMR 4610, Université de Lyon, Université Claude Bernard Lyon 1, Hospices Civils de Lyon, Faculté de médecine RTH Laennec, rue Guillaume Paradin, F-69008 Lyon, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Engineering temperature sensitive live attenuated influenza vaccines from emerging viruses. Vaccine 2012; 30:3691-702. [PMID: 22449422 DOI: 10.1016/j.vaccine.2012.03.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 02/16/2012] [Accepted: 03/12/2012] [Indexed: 12/22/2022]
Abstract
The licensed live attenuated influenza A vaccine (LAIV) in the United States is created by making a reassortant containing six internal genes from a cold-adapted master donor strain (ca A/AA/6/60) and two surface glycoprotein genes from a circulating/emerging strain (e.g., A/CA/7/09 for the 2009/2010 H1N1 pandemic). Technologies to rapidly create recombinant viruses directly from patient specimens were used to engineer alternative LAIV candidates that have genomes composed entirely of vRNAs from pandemic or seasonal strains. Multiple mutations involved in the temperature-sensitive (ts) phenotype of the ca A/AA/6/60 master donor strain were introduced into a 2009 H1N1 pandemic strain rA/New York/1682/2009 (rNY1682-WT) to create rNY1682-TS1, and additional mutations identified in other ts viruses were added to rNY1682-TS1 to create rNY1682-TS2. Both rNY1682-TS1 and rNY1682-TS2 replicated efficiently at 30°C and 33°C. However, rNY1682-TS1 was partially restricted, and rNY1682-TS2 was completely restricted at 39°C. Additionally, engineering the TS1 or TS2 mutations into a distantly related human seasonal H1N1 influenza A virus also resulted pronounced restriction of replication in vitro. Clinical symptoms and virus replication in the lungs of mice showed that although rNY1682-TS2 and the licensed FluMist(®)-H1N1pdm LAIV that was used to combat the 2009/2010 pandemic were similarly attenuated, the rNY1682-TS2 was more protective upon challenge with a virulent mutant of pandemic H1N1 virus or a heterologous H1N1 (A/PR/8/1934) virus. This study demonstrates that engineering key temperature sensitive mutations (PB1-K391E, D581G, A661T; PB2-P112S, N265S, N556D, Y658H) into the genomes of influenza A viruses attenuates divergent human virus lineages and provides an alternative strategy for the generation of LAIVs.
Collapse
|
9
|
The highly conserved arginine residues at positions 76 through 78 of influenza A virus matrix protein M1 play an important role in viral replication by affecting the intracellular localization of M1. J Virol 2011; 86:1522-30. [PMID: 22090133 DOI: 10.1128/jvi.06230-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Influenza A virus matrix protein (M1) plays an important role in virus assembly and budding. Besides a well-characterized basic amino acid-rich nuclear localization signal region at positions 101 to 105, M1 contains another basic amino acid stretch at positions 76-78 that is highly conserved among influenza A and B viruses, suggesting the importance of this stretch. To understand the role of these residues in virus replication, we mutated them to either lysine (K), alanine (A), or aspartic acid (D). We could generate viruses possessing either single or combination substitutions with K or single substitution with A at any of these positions, but not those with double substitutions with A or a single substitution with D. Viruses with the single substitution with A exhibited slower growth and had lower nucleoprotein/M1 quantitative ratio in virions compared to the wild-type virus. In cells infected with a virus possessing the single substitution with A at position 77 or 78 (R77A or R78A, respectively), the mutated M1 localized in patches at the cell periphery where nucleoprotein and hemagglutinin colocalized more often than the wild-type did. Transmission electron microscopy showed that virus possessing M1 R77A or R78A, but not the wild-type virus, was present in vesicular structures, indicating a defect in virus assembly and/or budding. The M1 mutations that did not support virus generation exhibited an aberrant M1 intracellular localization and affected protein incorporation into virus-like particles. These results indicate that the basic amino acid stretch of M1 plays a critical role in influenza virus replication.
Collapse
|
10
|
Optimizing viral protein yield of influenza virus strain A/Vietnam/1203/2004 by modification of the neuraminidase gene. J Virol 2009; 83:4023-9. [PMID: 19224999 DOI: 10.1128/jvi.02391-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The preparation of high-yield prepandemic influenza virus H5N1 strains has presented a challenge to both researchers and vaccine manufacturers. The reasons for the relatively low yield of the H5N1 strains are not fully understood, but it might be partially dependent on the interactions between the hemagglutinin (HA) or neuraminidase (NA) surface glycoprotein and other influenza virus proteins. In this study, we have constructed chimeras between the A/Puerto Rico/8/34 (PR8) NA gene and the A/Vietnam/1203/2004 (VN1203) NA gene that have resulted in an increase in the virus yield of the reassortant viruses without a significant loss of NA activity. By combining the amino terminus of NA from the PR8 strain with the carboxy terminus of NA from VN1203, the surface epitopes unique to the H5N1 VN1203 NA glycoprotein are maintained. This reassortant virus had a higher titer and total protein yield in eggs, grew to a higher titer, produced large plaques on MDCK cells, and retained NA activity. This work describes a novel recombinant technique designed to increase the yields of vaccine candidates for the production of pandemic influenza virus vaccines. The relationship between the infectivity and protein yield of the reassortants also is discussed.
Collapse
|
11
|
Thaa B, Herrmann A, Veit M. The polybasic region is not essential for membrane binding of the matrix protein M1 of influenza virus. Virology 2008; 383:150-5. [PMID: 19004463 DOI: 10.1016/j.virol.2008.10.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2008] [Revised: 09/10/2008] [Accepted: 10/01/2008] [Indexed: 10/21/2022]
Abstract
The matrix protein M1, the organizer of assembly of influenza virus, interacts with other virus components and with cellular membranes. It has been proposed that M1 binding to lipids is mediated by its polybasic region, but this could hitherto not been investigated in vivo since M1 accumulates in the nucleus of transfected cells. We have equipped M1 with nuclear export signals and showed that the constructs are bound to cellular membranes. Exchange of the complete polybasic region and of further hydrophobic amino acids in its vicinity did not prevent association of M1 with membranes. We therefore suppose that M1 probably interacts with membranes via multiple binding sites.
Collapse
Affiliation(s)
- Bastian Thaa
- Department of Immunology and Molecular Biology Veterinary Faculty, Free University Berlin, Philippstr. 13, 10115 Berlin, Germany
| | | | | |
Collapse
|
12
|
Studies of an influenza A virus temperature-sensitive mutant identify a late role for NP in the formation of infectious virions. J Virol 2008; 83:562-71. [PMID: 18987140 DOI: 10.1128/jvi.01424-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influenza A virus nucleoprotein (NP) is a single-stranded RNA-binding protein that encapsidates the virus genome and has essential functions in viral-RNA synthesis. Here, we report the characterization of a temperature-sensitive (ts) NP mutant (US3) originally generated in fowl plague virus (A/chicken/Rostock/34). Sequence analysis revealed a single mutation, M239L, in NP, consistent with earlier mapping studies assigning the ts lesion to segment 5. Introduction of this mutation into A/PR/8/34 virus by reverse genetics produced a ts phenotype, confirming the identity of the lesion. Despite an approximately 100-fold drop in the viral titer at the nonpermissive temperature, the mutant US3 polypeptide supported wild-type (WT) levels of genome transcription, replication, and protein synthesis, indicating a late-stage defect in function of the NP polypeptide. Nucleocytoplasmic trafficking of the US3 NP was also normal, and the virus actually assembled and released around sixfold more virus particles than the WT virus, with normal viral-RNA content. However, the particle/PFU ratio of these virions was 50-fold higher than that of WT virus, and many particles exhibited an abnormal morphology. Reverse-genetics studies in which A/PR/8/34 segment 7 was swapped with sequences from other strains of virus revealed a profound incompatibility between the M239L mutation and the A/Udorn/72 M1 gene, suggesting that the ts mutation affects M1-NP interactions. Thus, we have identified a late-acting defect in NP that, separate from its function in RNA synthesis, indicates a role for the polypeptide in virion assembly, most likely involving M1 as a partner.
Collapse
|
13
|
Ketha KMV, Atreya CD. Application of bioinformatics-coupled experimental analysis reveals a new transport-competent nuclear localization signal in the nucleoprotein of influenza A virus strain. BMC Cell Biol 2008; 9:22. [PMID: 18442378 PMCID: PMC2386121 DOI: 10.1186/1471-2121-9-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 04/28/2008] [Indexed: 11/10/2022] Open
Abstract
Background Two nuclear localization sequences (NLS) in influenza A virus nucleoprotein (NP) have been demonstrated to be critical for nuclear import of NP and viral ribonucleoprotein complexes. However, a deletion mutant lacking these two signals was still able to localize to the nucleus suggesting the presence of yet another (a third) potential NLS in the NP protein. In order to identify the nature of this potential NLS signal in the NP of a WS/33L influenza virus A strain, we utilized the tools of bioinformatics coupled with functional experimental analyses in the present study. Results Comparison of the deduced aa sequence of NP of WS/33L strain with the published WS/33 NP sequences revealed that a single amino acid (aa) change (Met to Arg) at position 105 results in converting the flanking regions (between aa position 90–121, a 32-residue stretch) into two classical overlapping bipartite NLS (obpNLS). GenBank search revealed that 9 out of 500 published NP sequences contain a similar Arg at position 105 (instead of Met) with a 100% homology to the obpNLS region. Various NP-green fluorescent protein (GFP) fusion constructs with and without the signal (obpNLS-Arg105) were utilized to understand the functional nature of this signal. We analyzed the transport competency of the expressed chimeric proteins in terms of their cellular localization by confocal immunofluorescence assay. Our analysis revealed that all NP-GFP constructs containing the wild-type (R105) sequence localized predominantly to the nucleus. Constructs lacking the obpNLS or constructs with reverse mutation (R105 to M105) on the other hand exhibited predominant cytoplasmic localization pattern. Interestingly, when the 32 aa obpNLS was fused with an unrelated viral protein (rotavirus NSP6) that has been known to be cytoplasmic protein, the chimeric protein (obpNLS-NSP6) was efficiently transported into the nucleus, indicating an efficient nuclear transport function of the 32-residue obpNLS in the NP of WS/33L strain of influenza A virus. Conclusion This report while not only establishing a new NLS in the influenza A virus strain, it also reinforces the idea that proper application of bioinformatics-coupled experimental analysis serves as a powerful tool in identifying new functional signals in proteins of interest.
Collapse
Affiliation(s)
- Krishna Mohan V Ketha
- Section of Cell Biology, Laboratory of Cellular Hematology, Division of Hematology, Office of Blood Research and Review, Center for Biologics Evaluation and Research (F,D,A,) Bethesda, MD 20892, USA.
| | | |
Collapse
|
14
|
Noton SL, Medcalf E, Fisher D, Mullin AE, Elton D, Digard P. Identification of the domains of the influenza A virus M1 matrix protein required for NP binding, oligomerization and incorporation into virions. J Gen Virol 2007; 88:2280-2290. [PMID: 17622633 PMCID: PMC2884976 DOI: 10.1099/vir.0.82809-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The matrix (M1) protein of influenza A virus is a multifunctional protein that plays essential structural and functional roles in the virus life cycle. It drives virus budding and is the major protein component of the virion, where it forms an intermediate layer between the viral envelope and integral membrane proteins and the genomic ribonucleoproteins (RNPs). It also helps to control the intracellular trafficking of RNPs. These roles are mediated primarily via protein–protein interactions with viral and possibly cellular proteins. Here, the regions of M1 involved in binding the viral RNPs and in mediating homo-oligomerization are identified. In vitro, by using recombinant proteins, it was found that the middle domain of M1 was responsible for binding NP and that this interaction did not require RNA. Similarly, only M1 polypeptides containing the middle domain were able to bind to RNP–M1 complexes isolated from purified virus. When M1 self-association was examined, all three domains of the protein participated in homo-oligomerization although, again, the middle domain was dominant and self-associated efficiently in the absence of the N- and C-terminal domains. However, when the individual fragments of M1 were tagged with green fluorescent protein and expressed in virus-infected cells, microscopy of filamentous particles showed that only full-length M1 was incorporated into budding virions. It is concluded that the middle domain of M1 is primarily responsible for binding NP and self-association, but that additional interactions are required for efficient incorporation of M1 into virus particles.
Collapse
Affiliation(s)
- Sarah L Noton
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Elizabeth Medcalf
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Dawn Fisher
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Anne E Mullin
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Debra Elton
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Paul Digard
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| |
Collapse
|
15
|
Snippe M, Willem Borst J, Goldbach R, Kormelink R. Tomato spotted wilt virus Gc and N proteins interact in vivo. Virology 2006; 357:115-23. [PMID: 16963098 DOI: 10.1016/j.virol.2006.06.037] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 04/05/2006] [Accepted: 06/07/2006] [Indexed: 11/23/2022]
Abstract
Tomato spotted wilt virus (TSWV) virions consist of a nucleocapsid core surrounded by a membrane containing glycoproteins Gn and Gc. To unravel the protein interactions involved in the membrane acquisition of RNPs, TSWV nucleocapsid protein (N), Gn and Gc were expressed and analyzed in BHK21 cells. Upon coexpression of Gn, Gc and N, a partial colocalization of N with both glycoproteins was observed in the Golgi region. In contrast, upon coexpression of Gc and N in the absence of Gn, both proteins colocalized to a distinct non-Golgi perinuclear region. Using FLIM and FRET, interaction was demonstrated between N and Gc, but not between N and Gn, and was only observed in the region where both proteins accumulated. The genuine character of N-Gc interaction was confirmed by its presence in purified virus and RNP preparations. The results are discussed in view of TSWV particle assembly taking place at the Golgi complex.
Collapse
Affiliation(s)
- Marjolein Snippe
- Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands
| | | | | | | |
Collapse
|
16
|
Bourmakina SV, García-Sastre A. The morphology and composition of influenza A virus particles are not affected by low levels of M1 and M2 proteins in infected cells. J Virol 2005; 79:7926-32. [PMID: 15919950 PMCID: PMC1143655 DOI: 10.1128/jvi.79.12.7926-7932.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We generated a recombinant influenza A virus (Mmut) that produced low levels of matrix (M1) and M2 proteins in infected cells. Mmut virus propagated to significantly lower titers than did wild-type virus in cells infected at low multiplicity. By contrast, virion morphology and incorporation of viral proteins and vRNAs into virus particles were similar to those of wild-type virus. We propose that a threshold amount of M1 protein is needed for the assembly of viral components into an infectious particle and that budding is delayed in Mmut virus-infected cells until sufficient levels of M1 protein accumulate at the plasma membrane.
Collapse
Affiliation(s)
- Svetlana V Bourmakina
- Department of Microbiology, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, Box 1124, New York, NY 10029, USA
| | | |
Collapse
|
17
|
Abstract
The matrix protein (M1) of influenza virus plays an essential role in viral replication. Our previous studies have shown that basic amino acids 101RKLKR105 of M1 are involved in RNP binding and nuclear localization. For the present work, the functions of 101RKLKR105 were studied by introducing mutations into the M gene of influenza virus A/WSN/33 by reverse genetic methods. Individual substitution, R101S or R105S, had a minimal effect on viral replication. In contrast, the double mutation R101S-R105S was synergistic and resulted in temperature sensitivity reflected by reduced viral replication at a restrictive temperature. To investigate the in vivo effect on infection, BALB/c mice were infected with either A/WSN/33 wild-type (Wt) or mutant viruses and assessed for signs of illness, viral replication in the lungs, and survival rates. The results from mouse studies indicated that the R101S-R105S double mutant virus was strongly attenuated, while single mutant viruses R101S and R105S were minimally attenuated compared to A/WSN33 Wt under the same conditions. In challenge studies, mice immunized by infection with R101S-R105S were fully protected from lethal challenge with A/WSN/33. The replication and attenuating properties of R101S-R105S suggest its potential in development of live influenza virus vaccines.
Collapse
Affiliation(s)
- Teresa Liu
- Laboratory of Pediatric and Respiratory Viral Diseases, Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, USA
| | | |
Collapse
|