Displaying publications 1 - 20 of 33 in total

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  1. Identification of phosphoprotein:phosphoprotein and phosphoprotein:nucleocapsid protein interaction domains of the Newcastle disease virus
    Jahanshiri F, Eshaghi M, Yusoff K
    Arch Virol, 2005 Mar;150(3):611-8.
    PMID: 15592890
    The yeast two-hybrid system has been used to identify domains of the Newcastle disease virus (NDV) phosphoprotein (P) involved in self-association and interaction with the nucleocapsid protein (NP). Deletion analysis was used to map the domain(s) of the P protein involved in P:P and P:NP interactions. The C-terminal 45 amino acids (residues 247-291) were shown to play a major role in both of the interactions. Comparison of these findings with other reports suggests that paramyxoviruses are different with respect to interaction domain(s) between these two essential viral proteins involved in genome replication.
    Matched MeSH terms: Viral Proteins/metabolism*
  2. Chimeric Newcastle disease virus nucleocapsid with parts of viral hemagglutinin-neuraminidase and fusion proteins
    Rabu A, Tan WS, Kho CL, Omar AR, Yusoff K
    Acta Virol., 2002;46(4):211-7.
    PMID: 12693857
    The nucleocapsid (NP) protein of Newcastle disease virus (NDV) self-assembled in Escherichia coli as ring-like and herringbone-like particles. Several chimeric NP proteins were constructed in which the antigenic regions of the hemagglutinin-neuraminidase (HN) and fusion (F) proteins of NDV, myc epitope, and six histidines (a hexa-His tag) were linked to the C-terminus of the NP monomer. These chimeric proteins were expressed efficiently in soluble form in E. coli as detected by Western blot analysis. Electron microscopy of the purified products revealed that they self-assembled into ring-like particles. These chimeric particles exhibited antigenicity of the myc epitope, suggesting that the foreign sequences were exposed on the surface of the particles. Chickens inoculated with the chimeric particles mounted an immune response against NDV, suggesting the possibility of use of the ring-like particle as a carrier of immunogens in subunit vaccines and immunological reagents.
    Matched MeSH terms: Viral Proteins/metabolism
  3. Regions on nucleocapsid protein of Newcastle disease virus that interact with its phosphoprotein
    Kho CL, Tan WS, Tey BT, Yusoff K
    Arch Virol, 2004 May;149(5):997-1005.
    PMID: 15098113 DOI: 10.1007/s00705-003-0273-8
    The nucleocapsid (NP) and phospho-(P) proteins of paramyxoviruses are involved in transcription and replication of the viral genome. An in vitro protein binding assay was used to investigate the regions on NP protein that interact with the P protein of Newcastle disease virus (NDV). Truncated NP mutants were first immobilised on a solid phase and then interacted with radio-labelled [(35)S]-P protein synthesised in rabbit reticulocyte. The interaction affinity was quantitated by measuring the radioactivity that was retained on the solid phase. Using this approach, a highly interactive region was identified to be resided at the first 25 amino acids of NP N-terminus. The interaction between these two proteins remained strong even with the removal of 114 amino acids from the C-terminal end of NP. However, it is possible that the 49 amino acids at the C-terminal end might have another contact region for P protein, which is not as critical as the N-terminal end. The interaction regions mapped in this study are significantly different from the other two paramyxoviruses: Sendai and measles viruses in which the C-termini of their NP proteins play an important role in binding to the P.
    Matched MeSH terms: Viral Proteins/metabolism*
  4. Fulltext Inhibition of dengue NS2B-NS3 protease and viral replication in Vero cells by recombinant retrocyclin-1
    Rothan HA, Han HC, Ramasamy TS, Othman S, Rahman NA, Yusof R
    BMC Infect Dis, 2012;12:314.
    PMID: 23171075 DOI: 10.1186/1471-2334-12-314
    Global resurgence of dengue virus infections in many of the tropical and subtropical countries is a major concern. Therefore, there is an urgent need for the development of successful drugs that are both economical and offer a long-lasting protection. The viral NS2B-NS3 serine protease (NS2B-NS3pro) is a promising target for the development of drug-like inhibitors, which are not available at the moment. In this study, we report retrocyclin-1 (RC-1) production in E. coli as a recombinant peptide to test against dengue NS2B-NS3pro.
    Matched MeSH terms: Viral Proteins/metabolism*
  5. Reinfection of adult cattle with rotavirus B during repeated outbreaks of epidemic diarrhea
    Hayashi M, Murakami T, Kuroda Y, Takai H, Ide H, Awang A, et al.
    Can. J. Vet. Res., 2016 Jul;80(3):189-96.
    PMID: 27408331
    Rotavirus B (RVB) infection in cattle is poorly understood. The objective of this study was to describe the epidemiological features of repeated outbreaks of epidemic diarrhea due to RVB infection in adult cattle on a large dairy farm complex in Japan. In October 2002, approximately 550 adult cows and approximately 450 in February 2005 had acute watery diarrhea at several farms on the complex. Four months before the first outbreak, RVB antibody-positive rates at subsequently affected farms were significantly lower than at non-affected farms (30% to 32% versus 61% to 67%). During the acute phase of both outbreaks, RVB antibody-positive rates in diarrheal cows tested were as low as 15% to 26%. Most of the farms affected in the second outbreak were also involved in the first outbreak. Some adult cows with RVB diarrhea in the first outbreak showed not only RVB seroresponse, but also RVB shedding in the second outbreak, although none of these cows developed diarrhea. Nucleotide sequences of the VP7 and VP4 genes revealed a close relationship between RVB strains in both outbreaks. Taken together, these results indicate that outbreaks of epidemic RVB diarrhea in adult cows might be influenced by herd immunity and could occur repeatedly at the same farms over several years. To our knowledge, this is the first report on repeated RVB infections in the same cattle.
    Matched MeSH terms: Viral Proteins/metabolism
  6. Comparative evaluation of three purification methods for the nucleocapsid protein of Newcastle disease virus from Escherichia coli homogenates
    Tan YP, Ling TC, Yusoff K, Tan WS, Tey BT
    J Microbiol, 2005 Jun;43(3):295-300.
    PMID: 15995649
    In the present study, the performances of conventional purification methods, packed bed adsorption (PBA), and expanded bed adsorption (EBA) for the purification of the nucleocapsid protein (NP) of Newcastle disease virus (NDV) from Escherichia coli homogenates were evaluated. The conventional methods for the recovery of NP proteins involved multiple steps, such as centrifugation, precipitation, dialysis, and sucrose gradient ultracentrifugation. For the PBA, clarified feedstock was used for column loading, while in EBA, unclarified feedstock was used. Streamline chelating immobilized with Ni2+ ion was used as an affinity ligand for both PBA and EBA. The final protein yield obtained in conventional and PBA methods was 1.26% and 5.56%, respectively. It was demonstrated that EBA achieved the highest final protein yield of 9.6% with a purification factor of 7. Additionally, the total processing time of the EBA process has been shortened by 8 times compared to that of the conventional method.
    Matched MeSH terms: Viral Proteins/metabolism
  7. Fulltext Review of Current Cell-Penetrating Antibody Developments for HIV-1 Therapy
    Che Nordin MA, Teow SY
    Molecules, 2018 Feb 06;23(2).
    PMID: 29415435 DOI: 10.3390/molecules23020335
    The discovery of highly active antiretroviral therapy (HAART) in 1996 has significantly reduced the global mortality and morbidity caused by the acquired immunodeficiency syndrome (AIDS). However, the therapeutic strategy of HAART that targets multiple viral proteins may render off-target toxicity and more importantly results in drug-resistant escape mutants. These have been the main challenges for HAART and refinement of this therapeutic strategy is urgently needed. Antibody-mediated treatments are emerging therapeutic modalities for various diseases. Most therapeutic antibodies have been approved by Food and Drug Administration (FDA) mainly for targeting cancers. Previous studies have also demonstrated the promising effect of therapeutic antibodies against HIV-1, but there are several limitations in this therapy, particularly when the viral targets are intracellular proteins. The conventional antibodies do not cross the cell membrane, hence, the pathogenic intracellular proteins cannot be targeted with this classical therapeutic approach. Over the years, the advancement of antibody engineering has permitted the therapeutic antibodies to comprehensively target both extra- and intra-cellular proteins in various infections and diseases. This review aims to update on the current progress in the development of antibody-based treatment against intracellular targets in HIV-1 infection. We also attempt to highlight the challenges and limitations in the development of antibody-based therapeutic modalities against HIV-1.
    Matched MeSH terms: Viral Proteins/metabolism
  8. Fulltext Diversity and Evolutionary Histories of Human Coronaviruses NL63 and 229E Associated with Acute Upper Respiratory Tract Symptoms in Kuala Lumpur, Malaysia
    Al-Khannaq MN, Ng KT, Oong XY, Pang YK, Takebe Y, Chook JB, et al.
    Am J Trop Med Hyg, 2016 05 04;94(5):1058-64.
    PMID: 26928836 DOI: 10.4269/ajtmh.15-0810
    The human alphacoronaviruses HCoV-NL63 and HCoV-229E are commonly associated with upper respiratory tract infections (URTI). Information on their molecular epidemiology and evolutionary dynamics in the tropical region of southeast Asia however is limited. Here, we analyzed the phylogenetic, temporal distribution, population history, and clinical manifestations among patients infected with HCoV-NL63 and HCoV-229E. Nasopharyngeal swabs were collected from 2,060 consenting adults presented with acute URTI symptoms in Kuala Lumpur, Malaysia, between 2012 and 2013. The presence of HCoV-NL63 and HCoV-229E was detected using multiplex polymerase chain reaction (PCR). The spike glycoprotein, nucleocapsid, and 1a genes were sequenced for phylogenetic reconstruction and Bayesian coalescent inference. A total of 68/2,060 (3.3%) subjects were positive for human alphacoronavirus; HCoV-NL63 and HCoV-229E were detected in 45 (2.2%) and 23 (1.1%) patients, respectively. A peak in the number of HCoV-NL63 infections was recorded between June and October 2012. Phylogenetic inference revealed that 62.8% of HCoV-NL63 infections belonged to genotype B, 37.2% was genotype C, while all HCoV-229E sequences were clustered within group 4. Molecular dating analysis indicated that the origin of HCoV-NL63 was dated to 1921, before it diverged into genotype A (1975), genotype B (1996), and genotype C (2003). The root of the HCoV-229E tree was dated to 1955, before it diverged into groups 1-4 between the 1970s and 1990s. The study described the seasonality, molecular diversity, and evolutionary dynamics of human alphacoronavirus infections in a tropical region.
    Matched MeSH terms: Viral Proteins/metabolism
  9. Fulltext In silico evidence of de novo interactions between ribosomal and Epstein - Barr virus proteins
    Sim EU, Talwar SP
    BMC Mol Cell Biol, 2019 08 15;20(1):34.
    PMID: 31416416 DOI: 10.1186/s12860-019-0219-y
    BACKGROUND: Association of Epstein-Barr virus (EBV) encoded latent gene products with host ribosomal proteins (RPs) has not been fully explored, despite their involvement in the aetiology of several human cancers. To gain an insight into their plausible interactions, we employed a computational approach that encompasses structural alignment, gene ontology analysis, pathway analysis, and molecular docking.

    RESULTS: In this study, the alignment analysis based on structural similarity allows the prediction of 48 potential interactions between 27 human RPs and the EBV proteins EBNA1, LMP1, LMP2A, and LMP2B. Gene ontology analysis of the putative protein-protein interactions (PPIs) reveals their probable involvement in RNA binding, ribosome biogenesis, metabolic and biosynthetic processes, and gene regulation. Pathway analysis shows their possible participation in viral infection strategies (viral translation), as well as oncogenesis (Wnt and EGFR signalling pathways). Finally, our molecular docking assay predicts the functional interactions of EBNA1 with four RPs individually: EBNA1-eS10, EBNA1-eS25, EBNA1-uL10 and EBNA1-uL11.

    CONCLUSION: These interactions have never been revealed previously via either experimental or in silico approach. We envisage that the calculated interactions between the ribosomal and EBV proteins herein would provide a hypothetical model for future experimental studies on the functional relationship between ribosomal proteins and EBV infection.

    Matched MeSH terms: Viral Proteins/metabolism*
  10. Fulltext Nucleoside Analogs with Selective Antiviral Activity against Dengue Fever and Japanese Encephalitis Viruses
    Zandi K, Bassit L, Amblard F, Cox BD, Hassandarvish P, Moghaddam E, et al.
    Antimicrob Agents Chemother, 2019 Jul;63(7).
    PMID: 31061163 DOI: 10.1128/AAC.00397-19
    Dengue virus (DENV) and Japanese encephalitis virus (JEV) are important arthropod-borne viruses from the Flaviviridae family. DENV is a global public health problem with significant social and economic impacts, especially in tropical and subtropical areas. JEV is a neurotropic arbovirus endemic to east and southeast Asia. There are no U.S. FDA-approved antiviral drugs available to treat or to prevent DENV and JEV infections, leaving nearly one-third of the world's population at risk for infection. Therefore, it is crucial to discover potent antiviral agents against these viruses. Nucleoside analogs, as a class, are widely used for the treatment of viral infections. In this study, we discovered nucleoside analogs that possess potent and selective anti-JEV and anti-DENV activities across all serotypes in cell-based assay systems. Both viruses were susceptible to sugar-substituted 2'-C-methyl analogs with either cytosine or 7-deaza-7-fluoro-adenine nucleobases. Mouse studies confirmed the anti-DENV activity of these nucleoside analogs. Molecular models were assembled for DENV serotype 2 (DENV-2) and JEV RNA-dependent RNA polymerase replication complexes bound to nucleotide inhibitors. These models show similarities between JEV and DENV-2, which recognize the same nucleotide inhibitors. Collectively, our findings provide promising compounds and a structural rationale for the development of direct-acting antiviral agents with dual activity against JEV and DENV infections.
    Matched MeSH terms: Viral Proteins/metabolism
  11. Nodamura virus B2 amino terminal domain sensitivity to small interfering RNA
    Ali PS, John J, Selvaraj M, Kek TL, Salleh MZ
    Microbiol. Immunol., 2015 May;59(5):299-304.
    PMID: 25753649 DOI: 10.1111/1348-0421.12253
    Nodamura virus (NoV) B2, a suppressor of RNA interference, binds double stranded RNAs (dsRNAs) and small interfering RNAs (siRNAs) corresponding to Dicer substrates and products. Here, we report that the amino terminal domain of NoV B2 (NoV B2 79) specifically binds siRNAs but not dsRNAs. NoV B2 79 oligomerizes on binding to 27 nucleotide siRNA. Mutation of the residues phenylalanine49 and alanine60 to cysteine and methionine, respectively enhances the RNA binding affinity of NoV B2 79. Circular dichroism spectra demonstrated that the wild type and mutant NoV B2 79 have similar secondary structure conformations.
    Matched MeSH terms: Viral Proteins/metabolism*
  12. Fulltext Doxycycline Interferes with Zika Virus Serine Protease and Inhibits Virus Replication in Human Skin Fibroblasts
    Chong Teoh T, J Al-Harbi S, Abdulrahman AY, Rothan HA
    Molecules, 2021 Jul 16;26(14).
    PMID: 34299596 DOI: 10.3390/molecules26144321
    Zika virus (ZIKV) represents a re-emerging threat to global health due to its association with congenital birth defects. ZIKV NS2B-NS3 protease is crucial for virus replication by cleaving viral polyprotein at various junctions to release viral proteins and cause cytotoxic effects in ZIKV-infected cells. This study characterized the inhibitory effects of doxycycline against ZIKV NS2B-NS3 protease and viral replication in human skin cells. The in silico data showed that doxycycline binds to the active site of ZIKV protease at a low docking energy (-7.8 Kcal/mol) via four hydrogen bonds with the protease residues TYR1130, SER1135, GLY1151, and ASP83. Doxycycline efficiently inhibited viral NS2B-NS3 protease at average human temperature (37 °C) and human temperature with a high fever during virus infection (40 °C). Interestingly, doxycycline showed a higher inhibitory effect at 40 °C (IC50 = 5.3 µM) compared to 37 °C (9.9 µM). The virus replication was considerably reduced by increasing the concentration of doxycycline. An approximately 50% reduction in virus replication was observed at 20 µM of doxycycline. Treatment with 20 µM of doxycycline reduced the cytopathic effects (CPE), and the 40 µM of doxycycline almost eliminated the CPE of human skin cells. This study showed that doxycycline binds to the ZIKV protease and inhibits its catalytic activity at a low micro-molecular concentration range. Treatment of human skin fibroblast with doxycycline eliminated ZIKV infection and protected the cells against the cytopathic effects of the infection.
    Matched MeSH terms: Viral Proteins/metabolism
  13. Fulltext CATH: increased structural coverage of functional space
    Sillitoe I, Bordin N, Dawson N, Waman VP, Ashford P, Scholes HM, et al.
    Nucleic Acids Res, 2021 Jan 08;49(D1):D266-D273.
    PMID: 33237325 DOI: 10.1093/nar/gkaa1079
    CATH (https://www.cathdb.info) identifies domains in protein structures from wwPDB and classifies these into evolutionary superfamilies, thereby providing structural and functional annotations. There are two levels: CATH-B, a daily snapshot of the latest domain structures and superfamily assignments, and CATH+, with additional derived data, such as predicted sequence domains, and functionally coherent sequence subsets (Functional Families or FunFams). The latest CATH+ release, version 4.3, significantly increases coverage of structural and sequence data, with an addition of 65,351 fully-classified domains structures (+15%), providing 500 238 structural domains, and 151 million predicted sequence domains (+59%) assigned to 5481 superfamilies. The FunFam generation pipeline has been re-engineered to cope with the increased influx of data. Three times more sequences are captured in FunFams, with a concomitant increase in functional purity, information content and structural coverage. FunFam expansion increases the structural annotations provided for experimental GO terms (+59%). We also present CATH-FunVar web-pages displaying variations in protein sequences and their proximity to known or predicted functional sites. We present two case studies (1) putative cancer drivers and (2) SARS-CoV-2 proteins. Finally, we have improved links to and from CATH including SCOP, InterPro, Aquaria and 2DProt.
    Matched MeSH terms: Viral Proteins/metabolism
  14. Fulltext Molecular characterization of Malaysian fowl adenovirus (FAdV) serotype 8b species E and pathogenicity of the virus in specific-pathogen-free chicken
    Sabarudin NS, Tan SW, Phang YF, Omar AR
    J Vet Sci, 2021 Jul;22(4):e42.
    PMID: 34313038 DOI: 10.4142/jvs.2021.22.e42
    BACKGROUND: Inclusion body hepatitis (IBH) is an economically important viral disease primarily affecting broiler and breeder chickens. All 12 serotypes of fowl adenovirus (FAdV) can cause IBH.

    OBJECTIVES: To characterize FAdV isolates based on phylogenetic analysis, and to study the pathogenicity of FAdV-8b in specific-pathogen-free (SPF) chickens following virus inoculation via oral and intramuscular (IM) routes.

    METHODS: Suspected organ samples were subjected to virus isolation and polymerase chain reaction (PCR) for FAdV detection. Hexon gene sequencing and phylogenetic analysis were performed on FAdV-positive samples for serotype identification. One FAdV-8b isolate, UPM/FAdV/420/2017, was selected for fiber gene characterization and pathogenicity study and was inoculated in SPF chickens via oral and IM routes.

    RESULTS: The hexon gene phylogenetic analysis revealed that all isolates belonged to FAdV-8b. The fiber gene-based phylogenetic analysis of isolate UPM/FAdV/420/2017 supported the grouping of that isolate into FAdV species E. Pathogenicity study revealed that, chickens infected with UPM/FAdV/420/2017 via the IM route had higher clinical score values, higher percent mortality, higher degree of the liver lesions, higher antibody response (p < 0.05), and higher virus shedding amounts (p < 0.05) than those infected via the oral route. The highest virus copy numbers were detected in liver and gizzard.

    CONCLUSIONS: FAdV-8b is the dominant FAdV serotype in Malaysia, and pathogenicity study of the FAdV-8b isolate UPM/FAdV/420/2017 indicated its ability to induce IBH in young SPF chickens when infected via oral or IM routes.

    Matched MeSH terms: Viral Proteins/metabolism
  15. Expression and purification of a recombinant scFv towards the exotoxin of the pathogen, Burkholderia pseudomallei
    Lim KP, Li H, Nathan S
    J Microbiol, 2004 Jun;42(2):126-32.
    PMID: 15357306
    A single chain variable fragment (scFv) specific towards B. pseudomallei exotoxin had previously been generated from an existing hybridoma cell line (6E6AF83B) and cloned into the phage display vector pComb3H. In this study, the scFv was subcloned into the pComb3X vector to facilitate the detection and purification of expressed antibodies. Detection was facilitated by the presence of a hemagglutinin (HA) tag, and purification was facilitated by the presence of a histidine tag. The culture was grown at 30 degrees C until log phase was achieved and then induced with 1 mM IPTG in the absence of any additional carbon source. Induction was continued at 30 degrees C for five h. The scFv was discerned by dual processes-direct enzyme-linked immunosorbent assays (ELISA), and Western blotting. When compared to E. coli strains ER2537 and HB2151, scFv expression was observed to be highest in the E. coli strain Top10F'. The expressed scFv protein was purified via nickel-mediated affinity chromatography and results indicated that two proteins a 52 kDa protein, and a 30 kDa protein were co-purified. These antibodies, when blotted against immobilized exotoxin, exhibited significant specificity towards the exotoxin, compared to other B. pseudomallei antigens. Thus, these antibodies should serve as suitable reagents for future affinity purification of the exotoxin.
    Matched MeSH terms: Viral Proteins/metabolism
  16. Recombineering linear BACs
    Chen Q, Narayanan K
    Methods Mol Biol, 2015;1227:27-54.
    PMID: 25239740 DOI: 10.1007/978-1-4939-1652-8_2
    Recombineering is a powerful genetic engineering technique based on homologous recombination that can be used to accurately modify DNA independent of its sequence or size. One novel application of recombineering is the assembly of linear BACs in E. coli that can replicate autonomously as linear plasmids. A circular BAC is inserted with a short telomeric sequence from phage N15, which is subsequently cut and rejoined by the phage protelomerase enzyme to generate a linear BAC with terminal hairpin telomeres. Telomere-capped linear BACs are protected against exonuclease attack both in vitro and in vivo in E. coli cells and can replicate stably. Here we describe step-by-step protocols to linearize any BAC clone by recombineering, including inserting and screening for presence of the N15 telomeric sequence, linearizing BACs in vivo in E. coli, extracting linear BACs, and verifying the presence of hairpin telomere structures. Linear BACs may be useful for functional expression of genomic loci in cells, maintenance of linear viral genomes in their natural conformation, and for constructing innovative artificial chromosome structures for applications in mammalian and plant cells.
    Matched MeSH terms: Viral Proteins/metabolism
  17. Induction of protein expression within Escherichia coli vector for entry into mammalian cells
    Chen Q, Lee CW, Sim EU, Narayanan K
    Hum Gene Ther Methods, 2014 Feb;25(1):40-7.
    PMID: 24134118 DOI: 10.1089/hgtb.2012.188
    Direct protein delivery into the cytosol of mammalian cells by invasive Escherichia coli (E. coli) bacterial vector will bypass the need to achieve nuclear entry and transcription of DNA, a major hurdle that is known to seriously limit gene transfer. The bacterial vector is induced to express the protein during its growth phase, before presentation for entry into mammalian cells and release of its content into the cellular environment. For this class of vector, crossing the plasma membrane becomes the primary step that determines the success of protein delivery. Yet, how the mechanics of protein expression within the vector affect its entry into the host is poorly understood. We found the vector's effectiveness to enter HeLa cells diminished together with its viability when phage N15 protelomerase (TelN) expression was induced continuously in the invasive E. coli despite producing an abundant amount of functional protein. By comparison, shorter induction, even as little as 3 hr, produced sufficient amounts of functional TelN and showed more effective invasion of HeLa cells, comparable to that of uninduced invasive E. coli. These results demonstrate that brief induction of protein expression during vector growth is essential for optimal entry into mammalian cells, an important step for achieving bacteria-mediated protein delivery.
    Matched MeSH terms: Viral Proteins/metabolism
  18. A Self-Replicating Linear DNA
    Liew PS, Tan TH, Wong YC, Sim EUH, Lee CW, Narayanan K
    ACS Synth Biol, 2020 04 17;9(4):804-813.
    PMID: 32196315 DOI: 10.1021/acssynbio.9b00478
    TelN and tos are a unique DNA linearization unit isolated from bacteriophage N15. While being transferable, the TelN cleaving-rejoining activities remained stable to function on tos in both bacterial and mammalian environments. However, TelN contribution in linear plasmid replication in mammalian cells remains unknown. Herein, we investigated the association of TelN in linear tos-containing DNA (tos-DNA) replication in mammalian cells. Additionally, the mammalian origin of replication (ori) that is well-known to initiate the replication event of plasmid vectors was also studied. In doing so, we identified that both TelN and mammalian initiation sites were essential for the replication of linear tos-DNA, determined by using methylation sensitive DpnI/MboI digestion and polymerase chain reaction (PCR) amplification approaches. Furthermore, we engineered the linear tos-DNA to be able to retain in mammalian cells using S/MAR technology. The resulting S/MAR containing tos-DNA was robust for at least 15 days, with (1) continuous tos-DNA replication, (2) correct splicing of gene transcripts, and (3) stable exogenous gene expression that was statistically comparable to the endogenous gene expression level. Understanding the activities of TelN and tos in mammalian cells can potentially provide insights for adapting this simple DNA linearization unit in developing novel genetic engineering tools, especially to the eukaryotic telomere/telomerase study.
    Matched MeSH terms: Viral Proteins/metabolism
  19. P-TEFb goes viral
    Zaborowska J, Isa NF, Murphy S
    Bioessays, 2016 07;38 Suppl 1:S75-85.
    PMID: 27417125 DOI: 10.1002/bies.201670912
    Positive transcription elongation factor b (P-TEFb), which comprises cyclin-dependent kinase 9 (CDK9) kinase and cyclin T subunits, is an essential kinase complex in human cells. Phosphorylation of the negative elongation factors by P-TEFb is required for productive elongation of transcription of protein-coding genes by RNA polymerase II (pol II). In addition, P-TEFb-mediated phosphorylation of the carboxyl-terminal domain (CTD) of the largest subunit of pol II mediates the recruitment of transcription and RNA processing factors during the transcription cycle. CDK9 also phosphorylates p53, a tumor suppressor that plays a central role in cellular responses to a range of stress factors. Many viral factors affect transcription by recruiting or modulating the activity of CDK9. In this review, we will focus on how the function of CDK9 is regulated by viral gene products. The central role of CDK9 in viral life cycles suggests that drugs targeting the interaction between viral products and P-TEFb could be effective anti-viral agents.
    Matched MeSH terms: Viral Proteins/metabolism*
  20. Fulltext Pathomechanisms, therapeutic targets and potent inhibitors of some beta-coronaviruses from bench-to-bedside
    Ayipo YO, Yahaya SN, Alananzeh WA, Babamale HF, Mordi MN
    Infect Genet Evol, 2021 Sep;93:104944.
    PMID: 34052418 DOI: 10.1016/j.meegid.2021.104944
    Since the emergence of their primitive strains, the complexity surrounding their pathogenesis, constant genetic mutation and translation are contributing factors to the scarcity of a successful vaccine for coronaviruses till moment. Although, the recent announcement of vaccine breakthrough for COVID-19 renews the hope, however, there remains a major challenge of accessibility to urgently match the rapid global therapeutic demand for curtailing the pandemic, thereby creating an impetus for further search. The reassessment of results from a stream of experiments is of enormous importance in identifying bona fide lead-like candidates to fulfil this quest. This review comprehensively highlights the common pathomechanisms and pharmacological targets of HCoV-OC43, SARS-CoV-1, MERS-CoV and SARS-CoV-2, and potent therapeutic potentials from basic and clinical experimental investigations. The implicated targets for the prevention and treatment include the viral proteases (Mpro, PLpro, 3CLpro), viral structural proteins (S- and N-proteins), non-structural proteins (nsp 3, 8, 10, 14, 16), accessory protein (ns12.9), viroporins (3a, E, 8a), enzymes (RdRp, TMPRSS2, ADP-ribosyltransferase, MTase, 2'-O-MTase, TATase, furin, cathepsin, deamidated human triosephosphate isomerase), kinases (MAPK, ERK, PI3K, mTOR, AKT, Abl2), interleukin-6 receptor (IL-6R) and the human host receptor, ACE2. Notably among the 109 overviewed inhibitors include quercetin, eriodictyol, baicalin, luteolin, melatonin, resveratrol and berberine from natural products, GC373, NP164 and HR2P-M2 from peptides, 5F9, m336 and MERS-GD27 from specific human antibodies, imatinib, remdesivir, ivermectin, chloroquine, hydroxychloroquine, nafamostat, interferon-β and HCQ from repurposing libraries, some iron chelators and traditional medicines. This review represents a model for further translational studies for effective anti-CoV therapeutic designs.
    Matched MeSH terms: Viral Proteins/metabolism
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