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Malwal S, Shang N, Liu W, Li X, Zhang L, Chen CC, Guo RT, Oldfield E. A Structural and Bioinformatics Investigation of a Fungal Squalene Synthase and Comparisons with Other Membrane Proteins. ACS OMEGA 2022; 7:22601-22612. [PMID: 35811857 PMCID: PMC9260892 DOI: 10.1021/acsomega.2c01924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
There is interest in the development of drugs to treat fungal infections due to the increasing threat of drug resistance, and here, we report the first crystallographic structure of the catalytic domain of a fungal squalene synthase (SQS), Aspergillus flavus SQS (AfSQS), a potential drug target, together with a bioinformatics study of fungal, human, and protozoal SQSs. Our X-ray results show strong structural similarities between the catalytic domains in these proteins, but, remarkably, using bioinformatics, we find that there is also a large, highly polar helix in the fungal proteins that connects the catalytic and membrane-anchoring transmembrane domains. This polar helix is absent in squalene synthases from all other lifeforms. We show that the transmembrane domain in AfSQS and in other SQSs, stannin, and steryl sulfatase, have very similar properties (% polar residues, hydrophobicity, and hydrophobic moment) to those found in the "penultimate" C-terminal helical domain in squalene epoxidase, while the final C-terminal domain in squalene epoxidase is more polar and may be monotopic. We also propose structural models for full-length AfSQS based on the bioinformatics results as well as a deep learning program that indicate that the C-terminus region may also be membrane surface-associated. Taken together, our results are of general interest given the unique nature of the polar helical domain in fungi that may be involved in protein-protein interactions as well as being a future target for antifungals.
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Affiliation(s)
- Satish
R. Malwal
- Department
of Chemistry, University of Illinois at
Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Na Shang
- Industrial
Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of
Sciences, Tianjin 300308, China
| | - Weidong Liu
- Industrial
Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of
Sciences, Tianjin 300308, China
| | - Xian Li
- State
Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative
Innovation Center for Green Transformation of Bio-resources, Hubei
Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Lilan Zhang
- State
Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative
Innovation Center for Green Transformation of Bio-resources, Hubei
Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Chun-Chi Chen
- State
Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative
Innovation Center for Green Transformation of Bio-resources, Hubei
Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Rey-Ting Guo
- State
Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative
Innovation Center for Green Transformation of Bio-resources, Hubei
Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Eric Oldfield
- Department
of Chemistry, University of Illinois at
Urbana-Champaign, Urbana, Illinois 61801, United States
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Lu Y, He P, Zhang Y, Ren Y, Zhang L. The emerging roles of retromer and sorting nexins in the life cycle of viruses. Virol Sin 2022; 37:321-330. [PMID: 35513271 PMCID: PMC9057928 DOI: 10.1016/j.virs.2022.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 04/12/2022] [Indexed: 02/06/2023] Open
Abstract
Retromer and sorting nexins (SNXs) transport cargoes from endosomes to the trans-Golgi network or plasma membrane. Recent studies have unveiled the emerging roles for retromer and SNXs in the life cycle of viruses, including members of Coronaviridae, Flaviviridae and Retroviridae. Key components of retromer/SNXs, such as Vps35, Vps26, SNX5 and SNX27, can affect multiple steps of the viral life cycle, including facilitating the entry of viruses into cells, participating in viral replication, and promoting the assembly of virions. Here we present a comprehensive updated review on the interplay between retromer/SNXs and virus, which will shed mechanistic insights into controlling virus infection. Retromer/SNXs could regulate viral infection directly or indirectly. Retromer/SNXs plays an important role for SARS-CoV-2 infection. HPV entry is mediated by retromer/SNXs. Retromer is required for HCV replication. Retromer affects the late step of HIV replication.
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Abstract
Virus entry, consisting of attachment to and penetration into the host target cell, is the first step of the virus life cycle and is a critical 'do or die' event that governs virus emergence in host populations. Most antiviral vaccines induce neutralizing antibodies that prevent virus entry into cells. However, while the prevention of virus invasion by humoral immunity is well appreciated, considerably less is known about the immune defences present within cells (known as intrinsic immunity) that interfere with virus entry. The interferon-induced transmembrane (IFITM) proteins, known for inhibiting fusion between viral and cellular membranes, were once the only factors known to restrict virus entry. However, the progressive development of genetic and pharmacological screening platforms and the onset of the COVID-19 pandemic have galvanized interest in how viruses infiltrate cells and how cells defend against it. Several host factors with antiviral potential are now implicated in the regulation of virus entry, including cholesterol 25-hydroxylase (CH25H), lymphocyte antigen 6E (LY6E), nuclear receptor co-activator protein 7 (NCOA7), interferon-γ-inducible lysosomal thiol reductase (GILT), CD74 and ARFGAP with dual pleckstrin homology domain-containing protein 2 (ADAP2). This Review summarizes what is known and what remains to be understood about the intrinsic factors that form the first line of defence against virus infection.
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Xie J, DiMaio D. Traptamer screening: a new functional genomics approach to study virus entry and other cellular processes. FEBS J 2022; 289:355-362. [PMID: 33604985 PMCID: PMC8371075 DOI: 10.1111/febs.15775] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/26/2021] [Accepted: 02/17/2021] [Indexed: 01/03/2023]
Abstract
Historically, the genetic analysis of mammalian cells entailed the isolation of randomly arising mutant cell lines with altered properties, followed by laborious genetic mapping experiments to identify the mutant gene responsible for the phenotype. In recent years, somatic cell genetics has been revolutionized by functional genomics screens, in which expression of every protein-coding gene is systematically perturbed, and the phenotype of the perturbed cells is determined. We outline here a novel functional genomics screening strategy that differs fundamentally from commonly used approaches. In this strategy, we express libraries of artificial transmembrane proteins named traptamers and select rare cells with the desired phenotype because, by chance, a traptamer specifically perturbs the expression or activity of a target protein. Active traptamers are then recovered from the selected cells and can be used as tools to dissect the biological process under study. We also briefly describe how we have used this new strategy to provide insights into the complex process by which human papillomaviruses enter cells.
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Affiliation(s)
- Jian Xie
- Department of Genetics, Yale School of Medicine, New Haven, CT USA
| | - Daniel DiMaio
- Department of Genetics, Yale School of Medicine, New Haven, CT USA
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT USA
- Yale Cancer Center, New Haven, CT USA
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Mikuličić S, Strunk J, Florin L. HPV16 Entry into Epithelial Cells: Running a Gauntlet. Viruses 2021; 13:v13122460. [PMID: 34960729 PMCID: PMC8706107 DOI: 10.3390/v13122460] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 12/16/2022] Open
Abstract
During initial infection, human papillomaviruses (HPV) take an unusual trafficking pathway through their host cell. It begins with a long period on the cell surface, during which the capsid is primed and a virus entry platform is formed. A specific type of clathrin-independent endocytosis and subsequent retrograde trafficking to the trans-Golgi network follow this. Cellular reorganization processes, which take place during mitosis, enable further virus transport and the establishment of infection while evading intrinsic cellular immune defenses. First, the fragmentation of the Golgi allows the release of membrane-encased virions, which are partially protected from cytoplasmic restriction factors. Second, the nuclear envelope breakdown opens the gate for these virus–vesicles to the cell nucleus. Third, the dis- and re-assembly of the PML nuclear bodies leads to the formation of modified virus-associated PML subnuclear structures, enabling viral transcription and replication. While remnants of the major capsid protein L1 and the viral DNA remain in a transport vesicle, the viral capsid protein L2 plays a crucial role during virus entry, as it adopts a membrane-spanning conformation for interaction with various cellular proteins to establish a successful infection. In this review, we follow the oncogenic HPV type 16 during its long journey into the nucleus, and contrast pro- and antiviral processes.
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Recent Advances in Our Understanding of the Infectious Entry Pathway of Human Papillomavirus Type 16. Microorganisms 2021; 9:microorganisms9102076. [PMID: 34683397 PMCID: PMC8540256 DOI: 10.3390/microorganisms9102076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 09/27/2021] [Indexed: 12/31/2022] Open
Abstract
Papillomaviruses are a diverse viral species, but several types such as HPV16 are given special attention due to their contribution towards the pathogenesis of several major cancers. In this review, we will summarize how the knowledge of HPV16 entry has expanded since the last comprehensive HPV16 entry review our lab published in 2017.
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Carse S, Bergant M, Schäfer G. Advances in Targeting HPV Infection as Potential Alternative Prophylactic Means. Int J Mol Sci 2021; 22:2201. [PMID: 33672181 PMCID: PMC7926419 DOI: 10.3390/ijms22042201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 01/22/2023] Open
Abstract
Infection by oncogenic human papillomavirus (HPV) is the primary cause of cervical cancer and other anogenital cancers. The majority of cervical cancer cases occur in low- and middle- income countries (LMIC). Concurrent infection with Human Immunodeficiency Virus (HIV) further increases the risk of HPV infection and exacerbates disease onset and progression. Highly effective prophylactic vaccines do exist to combat HPV infection with the most common oncogenic types, but the accessibility to these in LMIC is severely limited due to cost, difficulties in accessing the target population, cultural issues, and maintenance of a cold chain. Alternative preventive measures against HPV infection that are more accessible and affordable are therefore also needed to control cervical cancer risk. There are several efforts in identifying such alternative prophylactics which target key molecules involved in early HPV infection events. This review summarizes the current knowledge of the initial steps in HPV infection, from host cell-surface engagement to cellular trafficking of the viral genome before arrival in the nucleus. The key molecules that can be potentially targeted are highlighted, and a discussion on their applicability as alternative preventive means against HPV infection, with a focus on LMIC, is presented.
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Affiliation(s)
- Sinead Carse
- International Centre for Genetic Engineering and Biotechnology (ICGEB) Cape Town, Observatory 7925, South Africa;
- Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
| | - Martina Bergant
- Laboratory for Environmental and Life Sciences, University of Nova Gorica, Vipavska 13, 5000 Nova Gorica, Slovenia;
| | - Georgia Schäfer
- International Centre for Genetic Engineering and Biotechnology (ICGEB) Cape Town, Observatory 7925, South Africa;
- Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
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From APOBEC to ZAP: Diverse mechanisms used by cellular restriction factors to inhibit virus infections. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:382-394. [PMID: 30290238 PMCID: PMC6334645 DOI: 10.1016/j.bbamcr.2018.09.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/28/2018] [Accepted: 09/23/2018] [Indexed: 12/30/2022]
Abstract
Antiviral restriction factors are cellular proteins that inhibit the entry, replication, or spread of viruses. These proteins are critical components of the innate immune system and function to limit the severity and host range of virus infections. Here we review the current knowledge on the mechanisms of action of several restriction factors that affect multiple viruses at distinct stages of their life cycles. For example, APOBEC3G deaminates cytosines to hypermutate reverse transcribed viral DNA; IFITM3 alters membranes to inhibit virus membrane fusion; MXA/B oligomerize on viral protein complexes to inhibit virus replication; SAMHD1 decreases dNTP intracellular concentrations to prevent reverse transcription of retrovirus genomes; tetherin prevents release of budding virions from cells; Viperin catalyzes formation of a nucleoside analogue that inhibits viral RNA polymerases; and ZAP binds virus RNAs to target them for degradation. We also discuss countermeasures employed by specific viruses against these restriction factors, and mention secondary functions of several of these factors in modulating immune responses. These important examples highlight the diverse strategies cells have evolved to combat virus infections.
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Papillomaviruses and Endocytic Trafficking. Int J Mol Sci 2018; 19:ijms19092619. [PMID: 30181457 PMCID: PMC6163501 DOI: 10.3390/ijms19092619] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/24/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
Endocytic trafficking plays a major role in transport of incoming human papillomavirus (HPVs) from plasma membrane to the trans Golgi network (TGN) and ultimately into the nucleus. During this infectious entry, several cellular sorting factors are recruited by the viral capsid protein L2, which plays a critical role in ensuring successful transport of the L2/viral DNA complex to the nucleus. Later in the infection cycle, two viral oncoproteins, E5 and E6, have also been shown to modulate different aspects of endocytic transport pathways. In this review, we highlight how HPV makes use of and perturbs normal endocytic transport pathways, firstly to achieve infectious virus entry, secondly to produce productive infection and the completion of the viral life cycle and, finally, on rare occasions, to bring about the development of malignancy.
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Campos SK. Subcellular Trafficking of the Papillomavirus Genome during Initial Infection: The Remarkable Abilities of Minor Capsid Protein L2. Viruses 2017; 9:v9120370. [PMID: 29207511 PMCID: PMC5744145 DOI: 10.3390/v9120370] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/01/2017] [Accepted: 12/02/2017] [Indexed: 12/24/2022] Open
Abstract
Since 2012, our understanding of human papillomavirus (HPV) subcellular trafficking has undergone a drastic paradigm shift. Work from multiple laboratories has revealed that HPV has evolved a unique means to deliver its viral genome (vDNA) to the cell nucleus, relying on myriad host cell proteins and processes. The major breakthrough finding from these recent endeavors has been the realization of L2-dependent utilization of cellular sorting factors for the retrograde transport of vDNA away from degradative endo/lysosomal compartments to the Golgi, prior to mitosis-dependent nuclear accumulation of L2/vDNA. An overview of current models of HPV entry, subcellular trafficking, and the role of L2 during initial infection is provided below, highlighting unresolved questions and gaps in knowledge.
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Affiliation(s)
- Samuel K Campos
- The Department of Immunobiology, The University of Arizona, Tucson, AZ 85721-0240, USA.
- The Department of Molecular & Cellular Biology, The University of Arizona, Tucson, AZ 85721-0240, USA.
- The Cancer Biology Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ 85721-0240, USA.
- The BIO5 Institute, Tucson, AZ 85721-0240, USA.
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