Displaying publications 61 - 80 of 524 in total

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  1. Tang SS, Tan WS, Devi S, Wang LF, Pang T, Thong KL
    Clin Diagn Lab Immunol, 2003 Nov;10(6):1078-84.
    PMID: 14607870
    The capsular polysaccharide Vi antigen (ViCPS) is an essential virulence factor and also a protective antigen of Salmonella enterica serovar Typhi. A random 12-mer phage-displayed peptide library was used to identify mimotopes (epitope analogues) of this antigen by panning against a ViCPS-specific monoclonal antibody (MAb) ATVi. Approximately 75% of the phage clones selected in the fourth round carried the peptide sequence TSHHDSHGLHRV, and the rest of the clones harbored ENHSPVNIAHKL and other related sequences. These two sequences were also obtained in a similar panning process by using pooled sera from patients with a confirmed diagnosis of typhoid fever, suggesting they mimic immunodominant epitopes of ViCPS antigens. Binding of MAb ATVi to the mimotopes was specifically blocked by ViCPS, indicating that they interact with the same binding site (paratope) of the MAb. Data and reagents generated in this study have important implications for the development of peptide-base diagnostic tests and peptide vaccines and may also provide a better understanding of the pathogenesis of typhoid fever.
    Matched MeSH terms: Amino Acid Sequence
  2. Teh CS, Suhaili Z, Lim KT, Khamaruddin MA, Yahya F, Sajili MH, et al.
    Emerg Infect Dis, 2012 Jul;18(7):1177-9.
    PMID: 22709679 DOI: 10.3201/eid1807.111656
    A cholera outbreak in Terengganu, Malaysia, in November 2009 was caused by 2 El Tor Vibrio cholerae variants resistant to typical antimicrobial drugs. Evidence of replacement of treatable V. cholerae infection in the region with antimicrobial-resistant strains calls for increased surveillance and prevention measures.
    Matched MeSH terms: Amino Acid Sequence
  3. Khan AM, Hu Y, Miotto O, Thevasagayam NM, Sukumaran R, Abd Raman HS, et al.
    BMC Med Genomics, 2017 12 21;10(Suppl 4):78.
    PMID: 29322922 DOI: 10.1186/s12920-017-0301-2
    BACKGROUND: Viral vaccine target discovery requires understanding the diversity of both the virus and the human immune system. The readily available and rapidly growing pool of viral sequence data in the public domain enable the identification and characterization of immune targets relevant to adaptive immunity. A systematic bioinformatics approach is necessary to facilitate the analysis of such large datasets for selection of potential candidate vaccine targets.

    RESULTS: This work describes a computational methodology to achieve this analysis, with data of dengue, West Nile, hepatitis A, HIV-1, and influenza A viruses as examples. Our methodology has been implemented as an analytical pipeline that brings significant advancement to the field of reverse vaccinology, enabling systematic screening of known sequence data in nature for identification of vaccine targets. This includes key steps (i) comprehensive and extensive collection of sequence data of viral proteomes (the virome), (ii) data cleaning, (iii) large-scale sequence alignments, (iv) peptide entropy analysis, (v) intra- and inter-species variation analysis of conserved sequences, including human homology analysis, and (vi) functional and immunological relevance analysis.

    CONCLUSION: These steps are combined into the pipeline ensuring that a more refined process, as compared to a simple evolutionary conservation analysis, will facilitate a better selection of vaccine targets and their prioritization for subsequent experimental validation.

    Matched MeSH terms: Amino Acid Sequence
  4. Ng TS, Mohd Desa MN, Sandai D, Chong PP, Than LT
    Jundishapur J Microbiol, 2015 Nov;8(11):e25177.
    PMID: 26855740 DOI: 10.5812/jjm.25177
    BACKGROUND: The sensing mechanism of glucose in Saccharomyces cerevisiae is well studied. However, such information is scarcely found in other yeast species such as Candida glabrata.

    OBJECTIVES: This study aimed to identify the glucose sensing pathway related genes of C. glabrata and to analyze the regulation pattern of these genes in response to different surrounding glucose concentrations through the quantitative real time polymerase chain reaction (qRT-PCR).

    MATERIALS AND METHODS: Phylogenetic analysis was carried out on predicted amino acid sequences of C. glabrata and S. cerevisiae to compare their degree of similarity. In addition, the growth of C. glabrata in response to different amounts of glucose (0%, 0.01%, 0.1%, 1% and 2%) was evaluated via the spot dilution assay on prepared agar medium. Besides, the SNF3 and RGT2, which act as putative glucose sensors, and the RGT1 and MIG1, which act as putative transcriptional regulators and selected downstream hexose transporters (HXTs), were analysed through qRT-PCR analysis for the gene expression level under different glucose concentrations.

    RESULTS: Comparative analysis of predicted amino acids in the phylogenetic tree showed high similarity between C. glabrata and S cerevisiae. Besides, C. glabrata demonstrated the capability to grow in glucose levels as low as 0.01% in the spot dilution assay. In qRT-PCR analysis, differential expressions were observed in selected genes when C. glabrata was subjected to different glucose concentrations.

    CONCLUSIONS: The constructed phylogenetic tree suggests the close evolutionary relationship between C. glabrata and S. cerevisiae. The capability of C. glabrata to grow in extremely low glucose environments and the differential expression of selected glucose-sensing related genes suggested the possible role of these genes in modulating the growth of C. glabrata in response to different glucose concentrations. This study helps deepen our understanding of the glucose sensing mechanism in C. glabrata and serves to provide fundamental data that may assist in unveiling this mechanism as a potential drug target.

    Matched MeSH terms: Amino Acid Sequence
  5. Nurdin A, Hoshi Y, Yoneyama T, Miyauchi E, Tachikawa M, Watanabe M, et al.
    J Pharm Sci, 2016 Nov;105(11):3440-3452.
    PMID: 27665127 DOI: 10.1016/j.xphs.2016.08.013
    Prostate-specific antigen is currently the only protein biomarker routinely used as a diagnostic tool for early detection and treatment monitoring of prostate cancer. However, it remains questionable whether prostate-specific antigen-based screening can sensitively and selectively identify the presence and progression status of primary and metastatic prostate cancers. Hence, the purpose of this study was to identify potential biomarker candidates in the secretome of primary and metastatic prostate cancer cells by using a combination of global and targeted proteomics. Quantitative comparisons among secretome proteins derived from androgen-responsive primary cancer cells (P-22Rv1), androgen-irresponsive bone metastatic cancer cells (M-PC-3), and noncancerous prostate cells (N-PNT2) were performed using 2-dimensional image-converted analysis of liquid chromatography and mass spectrometry followed by in silico selection selected reaction monitoring analysis. Mediator of RNA polymerase II transcription subunit 13-like, insulin-like growth factor-binding protein 2, and hepatocyte growth factor were identified as highly secreted proteins from P-22Rv1 cells compared with N-PNT2 cells. Prostate-associated microseminoprotein, proactivator polypeptide, collagen-α-1 (VI) chain, and neuropilin-1 were identified as predominantly secreted proteins in M-PC-3 cells compared with N-PNT2 cells. These proteins in biological fluids are considered to be candidate biomarkers of primary and/or metastatic prostate cancer.
    Matched MeSH terms: Amino Acid Sequence
  6. Ung CY, Teoh TC
    J Biosci, 2014 Jun;39(3):493-504.
    PMID: 24845512
    DARPP-32 (dopamine and adenosine 3', 5'-monophosphate-regulated phosphoprotein of 32 kDa), which belongs to PPP1R1 gene family, is known to act as an important integrator in dopamine-mediated neurotransmission via the inhibition of protein phosphatase-1 (PP1). Besides its neuronal roles, this protein also behaves as a key player in pathological and pharmacological aspects. Use of bioinformatics and phylogenetics approaches to further characterize the molecular features of DARPP-32 can guide future works. Predicted phosphorylation sites on DARPP-32 show conservation across vertebrates. Phylogenetics analysis indicates evolutionary strata of phosphorylation site acquisition at the C-terminus, suggesting functional expansion of DARPP-32, where more diverse signalling cues may involve in regulating DARPP-32 in inhibiting PP1 activity. Moreover, both phylogenetics and synteny analyses suggest de novo origination of PPP1R1 gene family via chromosomal rearrangement and exonization.
    Matched MeSH terms: Amino Acid Sequence
  7. Aliza D, Ismail IS, Kuah MK, Shu-Chien AC, Tengku Muhammad TS
    Fish Physiol Biochem, 2008 Jun;34(2):129-38.
    PMID: 18649030 DOI: 10.1007/s10695-007-9153-6
    Copper is one of the major heavy metal pollutants found in the aquatic environment. Therefore, it is important for determining the genes that play a key role in copper metabolism in aquatic organisms. This study, thus, aimed to identify a new copper-inducible gene in swordtail fish, Xiphophorus helleri. Using ACP-based RT-PCR coupled with RLM-RACE, we cloned Wap65, a mammalian homologue of hemopexin gene. The gene exhibits high identity at amino acid levels with the Wap65 gene of other fish species (42-68%) and mammalian hemopexin gene (35-37%). In addition, ten cysteine and two histidine residues are conserved in the swordtail fish Wap65 gene. These cysteine residues are vital for structural integrity, and histidine residues provide high binding affinity towards heme. As revealed by RT-PCR, the gene was upregulated in swordtail fish that were exposed to copper in a dose- and time-dependent manner. Therefore, the identification of Wap65, a mammalian homologue of hemopexin, as a new copper-inducible gene will provide greater insight into the role of this gene in copper metabolism.
    Matched MeSH terms: Amino Acid Sequence
  8. Khoo BY, Samian MR, Najimudin N, Tengku Muhammad TS
    PMID: 12524031
    The coding region of guinea pig peroxisome proliferator activated receptor gamma1 (gpPPARgamma1) cDNA was successfully cloned from adipose tissue by reverse transcription polymerase chain reaction (RT-PCR) using the designated primers based on the conserved regions of the other mammalian PPARgamma1 sequence. From RT-PCR, a combination of three cDNA fragments that comprised of the full length coding region PPARgamma1 cDNA gene were amplified, with the size of 498, 550 and 557 bp, respectively. All three fragments were then successfully assembled by utilising the internal restriction sites present at the overlapping regions to give rise to the full-length coding region of gpPPARgamma1 with the size of 1428 bp and consisting of 475 amino acids. Guinea pig PPARgamma1 is highly conserved with those of other species at protein and nucleotide levels. Gene expression studies showed that gpPPARgamma mRNA was predominantly expressed in adipose tissue followed by lung and spleen. However, at the protein level, PPARgamma was also found to be expressed in skeletal muscle.
    Matched MeSH terms: Amino Acid Sequence
  9. Sim PF, Furusawa G, Teh AH
    Sci Rep, 2017 10 20;7(1):13656.
    PMID: 29057942 DOI: 10.1038/s41598-017-13288-1
    AlyQ from Persicobacter sp. CCB-QB2 is an alginate lyase with three domains - a carbohydrate-binding domain modestly resembling family 16 carbohydrate-binding module (CBM16), a family 32 CBM (CBM32) domain, and an alginate lyase domain belonging to polysaccharide lyase family 7 (PL7). Although AlyQ can also act on polyguluronate (poly-G) and polymannuronate (poly-M), it is most active on alginate. Studies with truncated AlyQ showed that the CBM32 domain did not contribute to enhancing AlyQ's activity under the assayed conditions. Nevertheless, it could bind to cleaved but not intact alginate, indicating that the CBM32 domain recognises alginate termini. The crystal structure containing both CBM32 and catalytic domains show that they do not interact with one another. The CBM32 domain contains a conserved Arg that may bind to the carboxyl group of alginate. The catalytic domain, meanwhile, shares a conserved substrate-binding groove, and the presence of two negatively charged Asp residues may dictate substrate specificity especially at subsite +1. As Persicobacter sp. CCB-QB2 was unable to utilise alginate, AlyQ may function to help the bacterium degrade cell walls more efficiently.
    Matched MeSH terms: Amino Acid Sequence
  10. Ng KT, Takebe Y, Kamarulzaman A, Tee KK
    Arch Virol, 2021 Jan;166(1):225-229.
    PMID: 33084935 DOI: 10.1007/s00705-020-04855-5
    Genome sequences of members of a potential fourth rhinovirus (RV) species, provisionally denoted as rhinovirus A clade D, from patients with acute respiratory infection were determined. Bayesian coalescent analysis estimated that clade D emerged around the 1940s and diverged further around 2006-2007 into two distinctive sublineages (RV-A8-like and RV-A45-like) that harbored unique "clade-defining" substitutions. Similarity plots and bootscan mapping revealed a recombination breakpoint located in the 5'-UTR region of members of the RV-A8-like sublineage. Phylogenetic reconstruction revealed the distribution of clade D viruses in the Asia Pacific region and in Europe, underlining its worldwide distribution.
    Matched MeSH terms: Amino Acid Sequence
  11. Sakkhachornphop S, Hadpech S, Wisitponchai T, Panto C, Kantamala D, Utaipat U, et al.
    Viruses, 2018 11 13;10(11).
    PMID: 30428529 DOI: 10.3390/v10110625
    Certain proteins have demonstrated proficient human immunodeficiency virus (HIV-1) life cycle disturbance. Recently, the ankyrin repeat protein targeting the HIV-1 capsid, AnkGAG1D4, showed a negative effect on the viral assembly of the HIV-1NL4-3 laboratory strain. To extend its potential for future clinical application, the activity of AnkGAG1D4 in the inhibition of other HIV-1 circulating strains was evaluated. Chimeric NL4-3 viruses carrying patient-derived Gag/PR-coding regions were generated from 131 antiretroviral drug-naïve HIV-1 infected individuals in northern Thailand during 2001⁻2012. SupT1, a stable T-cell line expressing AnkGAG1D4 and ankyrin non-binding control (AnkA32D3), were challenged with these chimeric viruses. The p24CA sequences were analysed and classified using the K-means clustering method. Among all the classes of virus classified using the p24CA sequences, SupT1/AnkGAG1D4 demonstrated significantly lower levels of p24CA than SupT1/AnkA32D3, which was found to correlate with the syncytia formation. This result suggests that AnkGAG1D4 can significantly interfere with the chimeric viruses derived from patients with different sequences of the p24CA domain. It supports the possibility of ankyrin-based therapy as a broad alternative therapeutic molecule for HIV-1 gene therapy in the future.
    Matched MeSH terms: Amino Acid Sequence
  12. Saoin S, Wisitponchai T, Intachai K, Chupradit K, Moonmuang S, Nangola S, et al.
    Asian Pac J Allergy Immunol, 2018 06;36(2):126-135.
    PMID: 28802032 DOI: 10.12932/AP-280217-0037
    BACKGROUND: AnkGAG1D4 is an artificial ankyrin repeat protein which recognizes the capsid protein (CA) of the human immunodeficiency virus type 1 (HIV-1) and exhibits the intracellular antiviral activity on the viral assembly process. Improving the binding affinity of AnkGAG1D4 would potentially enhance the AnkGAG1D4-mediated antiviral activity.

    OBJECTIVE: To augment the affinity of AnkGAG1D4 scaffold towards its CA target, through computational predictions and experimental designs.

    METHOD: Three dimensional structure of the binary complex formed by AnkGAG1D4 docked to the CA was used as a model for van der Waals (vdW) binding energy calculation. The results generated a simple guideline to select the amino acids for modifications. Following the predictions, modified AnkGAG1D4 proteins were produced and further evaluated for their CA-binding activity, using ELISA-modified method and bio-layer interferometry (BLI).

    RESULTS: Tyrosine at position 56 (Y56) in AnkGAG1D4 was experimentally identified as the most critical residue for CA binding. Rational substitutions of this residue diminished the binding affinity. However, vdW calculation preconized to substitute serine for tyrosine at position 45. Remarkably, the affinity for the viral CA was significantly enhanced in AnkGAG1D4-S45Y mutant, with no alteration of the target specificity.

    CONCLUSIONS: The S-to-Y mutation at position 45, based on the prediction of interacting amino acids and on vdW binding energy calculation, resulted in a significant enhancement of the affinity of AnkGAG1D4 ankyrin for its CA target. AnkGAG1D4-S45Y mutant represented the starting point for further construction of variants with even higher affinity towards the viral CA, and higher therapeutic potential in the future.

    Matched MeSH terms: Amino Acid Sequence
  13. Nithya R, Ahmed SA, Hoe CH, Gopinath SC, Citartan M, Chinni SV, et al.
    PLoS One, 2015;10(3):e0118668.
    PMID: 25774907 DOI: 10.1371/journal.pone.0118668
    Salmonellosis, a communicable disease caused by members of the Salmonella species, transmitted to humans through contaminated food or water. It is of paramount importance, to generate accurate detection methods for discriminating the various Salmonella species that cause severe infection in humans, including S. Typhi and S. Paratyphi A. Here, we formulated a strategy of detection and differentiation of salmonellosis by a multiplex polymerase chain reaction assay using S. Typhi non-protein coding RNA (sRNA) genes. With the designed sequences that specifically detect sRNA genes from S. Typhi and S. Paratyphi A, a detection limit of up to 10 pg was achieved. Moreover, in a stool-seeding experiment with S. Typhi and S. Paratyphi A, we have attained a respective detection limit of 15 and 1.5 CFU/mL. The designed strategy using sRNA genes shown here is comparatively sensitive and specific, suitable for clinical diagnosis and disease surveillance, and sRNAs represent an excellent molecular target for infectious disease.
    Matched MeSH terms: Amino Acid Sequence
  14. Goh ZH, Mohd NAS, Tan SG, Bhassu S, Tan WS
    J Gen Virol, 2014 Sep;95(Pt 9):1919-1928.
    PMID: 24878641 DOI: 10.1099/vir.0.064014-0
    White tail disease (WTD) kills prawn larvae and causes drastic losses to the freshwater prawn (Macrobrachium rosenbergii) industry. The main causative agent of WTD is Macrobrachium rosenbergii nodavirus (MrNV). The N-terminal end of the MrNV capsid protein is very rich in positively charged amino acids and is postulated to interact with RNA molecules. N-terminal and internal deletion mutagenesis revealed that the RNA-binding region is located at positions 20-29, where 80 % of amino acids are positively charged. Substitution of all these positively charged residues with alanine abolished the RNA binding. Mutants without the RNA-binding region still assembled into virus-like particles, suggesting that this region is not a part of the capsid assembly domain. This paper is, to the best of our knowledge, the first to report the specific RNA-binding region of MrNV capsid protein.
    Matched MeSH terms: Amino Acid Sequence
  15. Ong ST, Yusoff K, Kho CL, Abdullah JO, Tan WS
    J Gen Virol, 2009 Feb;90(Pt 2):392-397.
    PMID: 19141448 DOI: 10.1099/vir.0.005710-0
    The nucleocapsid protein of Nipah virus produced in Escherichia coli assembled into herringbone-like particles. The amino- and carboxy-termini of the N protein were shortened progressively to define the minimum contiguous sequence involved in capsid assembly. The first 29 aa residues of the N protein are dispensable for capsid formation. The 128 carboxy-terminal residues do not play a role in the assembly of the herringbone-like particles. A region with amino acid residues 30-32 plays a crucial role in the formation of the capsid particle. Deletion of any of the four conserved hydrophobic regions in the N protein impaired capsid formation. Replacement of the central conserved regions with the respective sequences from the Newcastle disease virus restored capsid formation.
    Matched MeSH terms: Amino Acid Sequence
  16. Tang KF, Abdullah MP, Yusoff K, Tan WS
    J Med Chem, 2007 Nov 15;50(23):5620-6.
    PMID: 17918821
    The core protein (HBcAg) of hepatitis B virus (HBV) has been shown to interact with the large surface antigen during HBV morphogenesis, and these interactions can be blocked by small peptides selected from either linear or constrained phage display peptide libraries. The association of HBcAg with peptide inhibitors was quantitatively evaluated by isothermal titration calorimetry. The thermodynamic data show that the interaction between HBcAg and peptide MHRSLLGRMKGA is enthalpy-driven and occurs at a 3:1 stoichiometry and dissociation constant (Kd) value of 79.4 muM. However, peptide WSFFSNI displays a higher binding affinity for HBcAg with a Kd value of 18.5 muM when compared to peptide MHRSLLGRMKGA. A combinatorial approach using chemical cross-linking and surface-enhanced laser desorption/ionization-time-of-flight-mass spectrometry shows that the Lys of peptide MHRSLLGRMKGA interacted either with D64, E77, or D78 of HBcAg.
    Matched MeSH terms: Amino Acid Sequence
  17. Tan GH, Yusoff K, Seow HF, Tan WS
    J Clin Virol, 2007 Jan;38(1):49-56.
    PMID: 17074533
    Phage display is an alternative method for constructing and selecting antibodies with desired specificity towards an antigen.
    Matched MeSH terms: Amino Acid Sequence
  18. Muhamad A, Ho KL, Rahman MB, Uhrín D, Tan WS
    Chem Biol Drug Des, 2013 Jun;81(6):784-94.
    PMID: 23405984 DOI: 10.1111/cbdd.12120
    A specific ligand targeting the immunodominant region of hepatitis B virus is desired in neutralizing the infectivity of the virus. In a previous study, a disulfide constrained cyclic peptide cyclo S(1) ,S(9) Cys-Glu-Thr-Gly-Ala-Lys-Pro-His-Cys (S(1) , S(9) -cyclo-CETGAKPHC) was isolated from a phage displayed cyclic peptide library using an affinity selection method against hepatitis B surface antigen. The cyclic peptide binds tightly to hepatitis B surface antigen with a relative dissociation constant (KD (rel) ) of 2.9 nm. The binding site of the peptide was located at the immunodominant region on hepatitis B surface antigen. Consequently, this study was aimed to elucidate the structure of the cyclic peptide and its interaction with hepatitis B surface antigen in silico. The solution structure of this cyclic peptide was solved using (1) H, (13) C, and (15) N NMR spectroscopy and molecular dynamics simulations with NMR-derived distance and torsion angle restraints. The cyclic peptide adopted two distinct conformations due to the isomerization of the Pro residue with one structured region in the ETGA sequence. Docking studies of the peptide ensemble with a model structure of hepatitis B surface antigen revealed that the cyclic peptide can potentially be developed as a therapeutic drug that inhibits the virus-host interactions.
    Matched MeSH terms: Amino Acid Sequence
  19. Tan WS
    J Gen Appl Microbiol, 2002 Apr;48(2):103-7.
    PMID: 12469306
    The long surface antigen (L-HBsAg) of hepatitis B virus (HBV) plays a central role in the production of infectious virions. During HBV morphogenesis, both the PreS and S domains of L-HBsAg form docking sites for the viral nucleocapsids. Thus, a compound that disrupts the interaction between the L-HBsAg and nucleocapsids could serve as a therapeutic agent against the virus based upon inhibition of morphogenesis. Synthetic peptides correspond to the binding sites in L-HBsAg inhibited the association of L-HBsAg with core antigen (HBcAg). A synthetic peptide carrying the epitope for a monoclonal antibody to the PreS1 domain competed weakly with L-HBsAg for HBcAg, but peptides corresponding to a linear sequence at the tip of the nucleocapsid spike did not, showing that the competing peptide does not resemble the tip of the spike.
    Matched MeSH terms: Amino Acid Sequence
  20. Gan BK, Yong CY, Ho KL, Omar AR, Alitheen NB, Tan WS
    Sci Rep, 2018 05 31;8(1):8499.
    PMID: 29855618 DOI: 10.1038/s41598-018-26749-y
    Skin cancer or cutaneous carcinoma, is a pre-eminent global public health problem with no signs of plateauing in its incidence. As the most common treatments for skin cancer, surgical resection inevitably damages a patient's appearance, and chemotherapy has many side effects. Thus, the main aim of this study was to screen for a cell penetrating peptide (CPP) for the development of a targeting vector for skin cancer. In this study, we identified a CPP with the sequence NRPDSAQFWLHH from a phage displayed peptide library. This CPP targeted the human squamous carcinoma A431 cells through an interaction with the epidermal growth factor receptor (EGFr). Methyl-β-cyclodextrin (MβCD) and chlorpromazine hydrochloride (CPZ) inhibited the internalisation of the CPP into the A431 cells, suggesting the peptide entered the cells via clathrin-dependent endocytosis. The CPP displayed on hepatitis B virus-like nanoparticles (VLNPs) via the nanoglue successfully delivered the nanoparticles into A431 cells. The present study demonstrated that the novel CPP can serve as a ligand to target and deliver VLNPs into skin cancer cells.
    Matched MeSH terms: Amino Acid Sequence
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