Displaying publications 1 - 20 of 48 in total

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  1. Mechanisms of action of 17βH-neriifolin on its anticancer effect in SKOV-3 ovarian cancer cell line
    Mutalip SS, Yunos NM, Abdul-Rahman PS, Jauri MH, Osman A, Adenan MI
    Anticancer Res, 2014 Aug;34(8):4141-51.
    PMID: 25075041
    AIM: Abnormalities in apoptotic signalling pathways often occur in cancer cells and limit the successful chemotherapy outcomes in cancers. Therefore, there is an urgent need to discover new anticancer agents with novel mechanisms of action to overcome the resistance effect in chemotherapy.

    MATERIALS AND METHODS: In the present study, the anticancer effects and the mechanisms of action of 17βH-neriifolin (cardiac glycoside) were evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and a proteomic approach in treated and non-treated SKOV-3 ovarian cancer cells.

    RESULTS: 17βH-neriifolin was found to be active with IC50 values of 0.01 ± 0.001 in SKOV-3 ovarian cancer cell line, as evaluated by the sulforhodamine B (SRB) assay. RESULTS from TUNEL assay indicated that 17βH-neriifolin caused apoptosis in SKOV-3 cells in a dose-dependent manner. Based on differential analysis of treated and non-treated SKOV-3 two-dimensional electrophoresis (2-DE) profiles, four proteins, namely vimentin (VIM), pyruvate kinase, muscle (PKM), heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) and transgelin (TAGLN1) were identified to be involved in apoptosis. Other proteins including piggybac transposable element derived 5 (PGBD5), DENN/MADD domain containing 2D (DENND2D) and formin-like 1(FMNL) have also been identified to be associated in SKOV-3 cell death induced by 17βH-neriifolin.

    CONCLUSION: These findings may provide new insights on the potential of 17βH-neriifolin's mechanism of action in killing ovarian cancer cells.

    Matched MeSH terms: Carrier Proteins/physiology; Membrane Proteins/physiology; Microfilament Proteins/physiology; Muscle Proteins/physiology
  2. Intracellular capacitive effects of polarized proteins in dendrites
    Poznanski RR, Cacha LA
    J Integr Neurosci, 2012 Dec;11(4):417-37.
    PMID: 23351050 DOI: 10.1142/S0219635212500264
    Passive dendrites become active as a result of electrostatic interactions by dielectric polarization in proteins in a segment of a dendrite. The resultant nonlinear cable equation for a cylindrical volume representation of a dendritic segment is derived from Maxwell's equations under assumptions: (i) the electric field is restricted longitudinally along the cable length; (ii) extracellular isopotentiality; (iii) quasi-electrostatic conditions; (iv) isotropic membrane and homogeneous medium with constant conductivity; and (v) protein polarization contributes to intracellular capacitive effects through a well defined nonlinear capacity-voltage characteristic; (vi) intracellular resistance and capacitance in parallel are connected to the membrane in series. Under the above hypotheses, traveling wave solutions of the cable equation are obtained as propagating fronts of electrical excitation associated with capacitive charge-equalization and dispersion of continuous polarization charge densities in an Ohmic cable. The intracellular capacitative effects of polarized proteins in dendrites contribute to the conduction process.
    Matched MeSH terms: Proteins/physiology*
  3. Fulltext Mutant p53 mediates survival of breast cancer cells
    Lim LY, Vidnovic N, Ellisen LW, Leong CO
    Br. J. Cancer, 2009 Nov 3;101(9):1606-12.
    PMID: 19773755 DOI: 10.1038/sj.bjc.6605335
    p53 is the most commonly mutated tumour-suppressor gene in human cancers. Unlike other tumour-suppressor genes, most p53 cancer mutations are missense mutations within the core domain, leading to the expression of a full-length mutant p53 protein. Accumulating evidence has indicated that p53 cancer mutants not only lose tumour suppression activity but also gain new oncogenic activities to promote tumourigenesis.
    Matched MeSH terms: DNA-Binding Proteins/physiology; Nuclear Proteins/physiology; Tumor Suppressor Proteins/physiology
  4. What proteins are involved in learning and memory?
    Perumal R, Tan I
    IUBMB Life, 2007 Jul;59(7):465-8.
    PMID: 17654123
    Matched MeSH terms: Proteins/physiology*
  5. Transcriptome-wide effects of expansin gene manipulation in etiolated Arabidopsis seedling
    Ilias IA, Negishi K, Yasue K, Jomura N, Morohashi K, Baharum SN, et al.
    J Plant Res, 2019 Mar;132(2):159-172.
    PMID: 30341720 DOI: 10.1007/s10265-018-1067-0
    Expansin is a non-enzymatic protein which plays a pivotal role in cell wall loosening by inducing stress relaxation and extension in the plant cell wall. Previous studies on Arabidopsis, Petunia × hybrida, and tomato demonstrated that the suppression of expansin gene expression reduced plant growth but expansin overexpression does not necessarily promotes growth. In this study, both expansin gene suppression and overexpression in dark-grown transgenic Arabidopsis seedlings resulted in reduced hypocotyl length at late growth stages with a more pronounced effect for the overexpression. This defect in hypocotyl elongation raises questions about the molecular effect of expansin gene manipulation. RNA-seq analysis of the transcriptomic changes between day 3 and day 5 seedlings for both transgenic lines found numerous differentially expressed genes (DEGs) including transcription factors and hormone-related genes involved in different aspects of cell wall development. These DEGs imply that the observed hypocotyl growth retardation is a consequence of the concerted effect of regulatory factors and multiple cell-wall related genes, which are important for cell wall remodelling during rapid hypocotyl elongation. This is further supported by co-expression analysis through network-centric approach of differential network cluster analysis. This first transcriptome-wide study of expansin manipulation explains why the effect of expansin overexpression is greater than suppression and provides insights into the dynamic nature of molecular regulation during etiolation.
    Matched MeSH terms: Plant Proteins/physiology*
  6. Alpha-hemoglobin-stabilizing protein (AHSP): a modulatory factor in β-thalassemia
    Che Yaacob NS, Islam MA, Alsaleh H, Ibrahim IK, Hassan R
    Int J Hematol, 2020 Mar;111(3):352-359.
    PMID: 31894534 DOI: 10.1007/s12185-019-02806-8
    Hemoglobin (Hb) is an iron-containing metalloprotein that transports oxygen molecules from the lungs to the rest of the human body. Among the different variants of Hb, HbA1 is the most common and is composed of two alpha (αHb) and two beta globin chains (βHb) constructing a heterotetrameric protein complex (α2β2). Due to the higher number of AHSP genes, there is a tendency to produce approximately twice as much of α subunit as β subunit. Therefore, there is a chance of presenting excess α subunit leftover in human blood plasma; excess subunits subsequently bind with each other and aggregates β-thalassemia occurs due to lack of or reduced numbers of βHb subunit. Alpha-hemoglobin-stabilizing protein (AHSP) is a scavenger protein which acts as a molecular chaperon by reversibly binding with free αHb forming a complex (AHSP-αHb) that prevents aggregation and precipitation preventing deleterious effects towards developing serious human diseases including β-thalassemia. Clinical severity worsens if mutations in AHSP gene co-occur in patients with β-thalassemia. Considering the mechanism of action of AHSP and its contribution to ameliorating β-thalassemia severity, it could potentially be used as a modulatory agent in the treatment of β-thalassemia.
    Matched MeSH terms: Blood Proteins/physiology*
  7. Fulltext The non-stop decay mRNA surveillance pathway is required for oxidative stress tolerance
    Jamar NH, Kritsiligkou P, Grant CM
    Nucleic Acids Res, 2017 Jun 20;45(11):6881-6893.
    PMID: 28472342 DOI: 10.1093/nar/gkx306
    Reactive oxygen species (ROS) are toxic by-products of normal aerobic metabolism. ROS can damage mRNAs and the translational apparatus resulting in translational defects and aberrant protein production. Three mRNA quality control systems monitor mRNAs for translational errors: nonsense-mediated decay, non-stop decay (NSD) and no-go decay (NGD) pathways. Here, we show that factors required for the recognition of NSD substrates and components of the SKI complex are required for oxidant tolerance. We found an overlapping requirement for Ski7, which bridges the interaction between the SKI complex and the exosome, and NGD components (Dom34/Hbs1) which have been shown to function in both NSD and NGD. We show that ski7 dom34 and ski7 hbs1 mutants are sensitive to hydrogen peroxide stress and accumulate an NSD substrate. We further show that NSD substrates are generated during ROS exposure as a result of aggregation of the Sup35 translation termination factor, which increases stop codon read-through allowing ribosomes to translate into the 3΄-end of mRNAs. Overexpression of Sup35 decreases stop codon read-through and rescues oxidant tolerance consistent with this model. Our data reveal an unanticipated requirement for the NSD pathway during oxidative stress conditions which prevents the production of aberrant proteins from NSD mRNAs.
    Matched MeSH terms: Cell Cycle Proteins/physiology; HSP70 Heat-Shock Proteins/physiology; GTP-Binding Proteins/physiology; Saccharomyces cerevisiae Proteins/physiology
  8. The requirements for sterol regulatory element-binding protein (Srebp) and stimulatory protein 1 (Sp1)-binding elements in the transcriptional activation of two freshwater fish Channa striata and Danio rerio elovl5 elongase
    Goh PT, Kuah MK, Chew YS, Teh HY, Shu-Chien AC
    Fish Physiol Biochem, 2020 Aug;46(4):1349-1359.
    PMID: 32239337 DOI: 10.1007/s10695-020-00793-w
    Fish are a major source of beneficial n-3 LC-PUFA in human diet, and there is considerable interest to elucidate the mechanism and regulatory aspects of LC-PUFA biosynthesis in farmed species. Long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis involves the activities of two groups of enzymes, the fatty acyl desaturase (Fads) and elongase of very long-chain fatty acid (Elovl). The promoters of elovl5 elongase, which catalyses the rate-limiting reaction of elongating polyunsaturated fatty acid (PUFA), have been previously described and characterized from several marine and diadromous teleost species. We report here the cloning and characterization of elovl5 promoter from two freshwater fish species, the carnivorous snakehead fish (Channa striata) and zebrafish. Results show the presence of sterol-responsive elements (SRE) in the core regulatory region of both promoters, suggesting the importance of sterol regulatory element-binding protein (Srebp) in the regulation of elovl5 for both species. Mutagenesis luciferase and electrophoretic mobility shift assays further validate the role of SRE for basal transcriptional activation. In addition, several Sp1-binding sites located in close proximity with SRE were present in the snakehead promoter, with one having a potential synergy with SRE in the regulation of elovl5 expression. The core zebrafish elovl5 promoter fragment also directed in vivo expression in the yolk syncytial layer of developing zebrafish embryos.
    Matched MeSH terms: Zebrafish Proteins/physiology*; Sterol Regulatory Element Binding Proteins/physiology*
  9. Fulltext ING2 (inhibitor of growth protein-2) plays a crucial role in preimplantation development
    Zhou L, Wang P, Zhang J, Heng BC, Tong GQ
    Zygote, 2016 Feb;24(1):89-97.
    PMID: 25672483 DOI: 10.1017/S0967199414000768
    ING2 (inhibitor of growth protein-2) is a member of the ING-gene family and participates in diverse cellular processes involving tumor suppression, DNA repair, cell cycle regulation, and cellular senescence. As a subunit of the Sin3 histone deacetylase complex co-repressor complex, ING2 binds to H3K4me3 to regulate chromatin modification and gene expression. Additionally, ING2 recruits histone methyltransferase (HMT) activity for gene repression, which is independent of the HDAC class I or II pathway. However, the physiological function of ING2 in mouse preimplantation embryo development has not yet been characterized previously. The expression, localization and function of ING2 during preimplantation development were investigated in this study. We showed increasing expression of ING2 within the nucleus from the 4-cell embryo stage onwards; and that down-regulation of ING2 expression by endoribonuclease-prepared small interfering RNA (esiRNA) microinjection results in developmental arrest during the morula to blastocyst transition. Embryonic cells microinjected with ING2-specific esiRNA exhibited decreased blastulation rate compared to the negative control. Further investigation of the underlying mechanism indicated that down-regulation of ING2 significantly increased expression of p21, whilst decreasing expression of HDAC1. These results suggest that ING2 may play a crucial role in the process of preimplantation embryo development through chromatin regulation.
    Matched MeSH terms: Homeodomain Proteins/physiology*; Tumor Suppressor Proteins/physiology*
  10. Fulltext Disruption of adeB gene has a greater effect on resistance to meropenems than adeA gene in Acinetobacter spp. isolated from University Malaya Medical Centre
    Wong EW, Yusof MY, Mansor MB, Anbazhagan D, Ong SY, Sekaran SD
    Singapore Med J, 2009 Aug;50(8):822-6.
    PMID: 19710984
    The AdeABC pump of Acinetobacter spp. confers resistance to various antibiotic classes. This pump is composed of the AdeA, AdeB, and AdeC proteins where AdeB is a member of the resistance-nodulation-division efflux pump superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively. In this study, an attempt is made to elucidate the role of the AdeABC efflux pump in carbapenem resistance in Acinetobacter spp.
    Matched MeSH terms: Bacterial Proteins/physiology; Membrane Transport Proteins/physiology
  11. Fulltext Development of a pyrG mutant of Aspergillus oryzae strain S1 as a host for the production of heterologous proteins
    Ling SO, Storms R, Zheng Y, Rodzi MR, Mahadi NM, Illias RM, et al.
    ScientificWorldJournal, 2013;2013:634317.
    PMID: 24381522 DOI: 10.1155/2013/634317
    The ease with which auxotrophic strains and genes that complement them can be manipulated, as well as the stability of auxotrophic selection systems, are amongst the advantages of using auxotrophic markers to produce heterologous proteins. Most auxotrophic markers in Aspergillus oryzae originate from chemical or physical mutagenesis that may yield undesirable mutations along with the mutation of interest. An auxotrophic A. oryzae strain S1 was generated by deleting the orotidine-5'-monophosphate decarboxylase gene (pyrG) by targeted gene replacement. The uridine requirement of the resulting strain GR6 pyrGΔ0 was complemented by plasmids carrying a pyrG gene from either Aspergillus nidulans or A. oryzae. β -Galactosidase expression by strain GR6 pyrGΔ0 transformed with an A. niger plasmid encoding a heterologous β -galactosidase was at least 150 times more than that obtained with the untransformed strain. Targeted gene replacement is thus an efficient way of developing auxotrophic mutants in A. oryzae and the auxotrophic strain GR6 pyrGΔ0 facilitated the production of a heterologous protein in this fungus.
    Matched MeSH terms: Fungal Proteins/physiology*
  12. Fulltext Enhanced production, purification, characterization and mechanism of action of salivaricin 9 lantibiotic produced by Streptococcus salivarius NU10
    Barbour A, Philip K, Muniandy S
    PLoS One, 2013;8(10):e77751.
    PMID: 24147072 DOI: 10.1371/journal.pone.0077751
    BACKGROUND: Lantibiotics are small lanthionine-containing bacteriocins produced by lactic acid bacteria. Salivaricin 9 is a newly discovered lantibiotic produced by Streptococcus salivarius. In this study we present the mechanism of action of salivaricin 9 and some of its properties. Also we developed new methods to produce and purify the lantibiotic from strain NU10.

    METHODOLOGY/PRINCIPAL FINDINGS: Salivaricin 9 was found to be auto-regulated when an induction assay was applied and this finding was used to develop a successful salivaricin 9 production system in liquid medium. A combination of XAD-16 and cation exchange chromatography was used to purify the secondary metabolite which was shown to have a molecular weight of approximately 3000 Da by SDS-PAGE. MALDI-TOF MS analysis indicated the presence of salivaricin 9, a 2560 Da lantibiotic. Salivaricin 9 is a bactericidal molecule targeting the cytoplasmic membrane of sensitive cells. The membrane permeabilization assay showed that salivaricin 9 penetrated the cytoplasmic membrane and induced pore formation which resulted in cell death. The morphological changes of test bacterial strains incubated with salivaricin 9 were visualized using Scanning Electron Microscopy which confirmed a pore forming mechanism of inhibition. Salivaricin 9 retained biological stability when exposed to high temperature (90-100°C) and stayed bioactive at pH ranging 2 to 10. When treated with proteinase K or peptidase, salivaricin 9 lost all antimicrobial activity, while it remained active when treated with lyticase, catalase and certain detergents.

    CONCLUSION: The mechanism of antimicrobial action of a newly discovered lantibiotic salivaricin 9 was elucidated in this study. Salivaricin 9 penetrated the cytoplasmic membrane of its targeted cells and induced pore formation. This project has given new insights on lantibiotic peptides produced by S. salivarius isolated from the oral cavities of Malaysian subjects.

    Matched MeSH terms: Bacterial Proteins/physiology
  13. Effects of pH on the functional properties of chicken muscle proteins- modified waxy cornstarch blends
    Zhang Q, Noryati I, Cheng LH
    J Food Sci, 2008 Mar;73(2):E82-7.
    PMID: 18298729 DOI: 10.1111/j.1750-3841.2007.00627.x
    Chicken breast muscle powder (CBMP) and modified waxy cornstarch (MWCS) blends were prepared at different pH conditions (pH 4, 5, 6, 7, 8, and 9). The blends were characterized by light microscopy, frequency sweep, flow analysis, and freeze-thaw stability analysis. Light microscopy showed that the blend structure was coarse at pH conditions close to the isoelectric point of protein and became finer with increasing pH. Frequency sweep demonstrated that the blend was more liquid-like with relatively lower storage (G') and loss (G'') moduli as the pH was increased from pH 4 to pH 9. Flow analysis revealed that thixotropy behavior was evident in samples treated at pHs 4 and 5, whereas antithixotropy was shown by those adjusted to pHs 6, 7, 8, and 9. The CBMP-MWCS blends were found to show better freeze-thaw stability at pH 8 that could be attributed to the formation of a highly interactive network structure of CBMP and MWCS.
    Matched MeSH terms: Muscle Proteins/physiology
  14. Proteomics of edible mushrooms: A mini-review
    Al-Obaidi JR
    Electrophoresis, 2016 05;37(10):1257-63.
    PMID: 26891916 DOI: 10.1002/elps.201600031
    Mushrooms are considered an important food for their traditionally famous nutritional and medicinal values, although much information about their potential at the molecular level is unfortunately unknown. Edible mushrooms include fungi that are either collected wild or cultivated. Many important species are difficult to cultivate but attempts have been made with varying degrees of success, with the results showing unsatisfactory economical cultivation methods. Recently, proteomic analysis has been developed as a powerful tool to study the protein content of fungi, particularly basidiomycetes. This mini-review article highlights the contribution of proteomics platforms to the study of edible mushrooms, focusing on the molecular mechanisms involved in developmental stages. This includes extracellular and cytoplasmic effector proteins that have potential or are involved in the synthesis of anticancer, antidiabetic, antioxidant, and antibiotic, in blood pressure control, in the supply of vitamins and minerals, and in other responses to environmental changes. The contribution of different proteomics techniques including classical and more advanced techniques is also highlighted.
    Matched MeSH terms: Fungal Proteins/physiology
  15. Fulltext Control of Polyamine Biosynthesis by Antizyme Inhibitor 1 Is Important for Transcriptional Regulation of Arginine Vasopressin in the Male Rat Hypothalamus
    Greenwood MP, Greenwood M, Paton JF, Murphy D
    Endocrinology, 2015 Aug;156(8):2905-17.
    PMID: 25961839 DOI: 10.1210/en.2015-1074
    The polyamines spermidine and spermine are small cations present in all living cells. In the brain, these cations are particularly abundant in the neurons of the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus, which synthesize the neuropeptide hormones arginine vasopressin (AVP) and oxytocin. We recently reported increased mRNA expression of antizyme inhibitor 1 (Azin1), an important regulator of polyamine synthesis, in rat SON and PVN as a consequence of 3 days of dehydration. Here we show that AZIN1 protein is highly expressed in both AVP- and oxytocin-positive magnocellular neurons of the SON and PVN together with antizyme 1 (AZ1), ornithine decarboxylase, and polyamines. Azin1 mRNA expression increased in the SON and PVN as a consequence of dehydration, salt loading, and acute hypertonic stress. In organotypic hypothalamic cultures, addition of the irreversible ornithine decarboxylase inhibitor DL-2-(difluoromethyl)-ornithine hydrochloride significantly increased the abundance of heteronuclear AVP but not heteronuclear oxytocin. To identify the function of Azin1 in vivo, lentiviral vectors that either overexpress or knock down Azin1 were stereotaxically delivered into the SON and/or PVN. Azin1 short hairpin RNA delivery resulted in decreased plasma osmolality and had a significant effect on food intake. The expression of AVP mRNA was also significantly increased in the SON by Azin1 short hairpin RNA. In contrast, Azin1 overexpression in the SON decreased AVP mRNA expression. We have therefore identified AZIN1, and hence by inference, polyamines as novel regulators of the expression of the AVP gene.
    Matched MeSH terms: Carrier Proteins/physiology*
  16. The role of chemical mediators in the pathogenesis of inflammation with emphasis on the kinin system
    Sharma JN, Mohsin SS
    Exp Pathol, 1990;38(2):73-96.
    PMID: 1971600
    In recent years, numerous agents have been recognized as inflammatory mediators. In this review, however, we discuss only those having direct relevance to human inflammatory diseases These mediators are clinically important due to their proinflammatory properties such as vasodilatation, increased vascular permeability, pain and chemotaxis. They may lead to the fifth cardinal sign, loss of function in inflammatory diseases. Agonists and non-specific antagonists are used as pharmacological tools to investigate the inflammatory role of PGs, LTs, PAF, IL-1, histamine, complement, SP, PMN-leukocytes, and kallikrein-kininogen-kinin systems. Unfortunately, no compound is known which concurrently abolishes all actions and interactions of inflammatory mediators. Therefore it would be highly useful to promote efforts in developing selective and competitive antagonists against proinflammatory actions of these chemical mediators. This may help to a better understanding of the pathogenesis of inflammatory reactions, and it may also be useful for the therapy of inflammatory diseases.
    Matched MeSH terms: Complement System Proteins/physiology
  17. Fulltext Curculin exhibits sweet-tasting and taste-modifying activities through its distinct molecular surfaces
    Kurimoto E, Suzuki M, Amemiya E, Yamaguchi Y, Nirasawa S, Shimba N, et al.
    J Biol Chem, 2007 Nov 16;282(46):33252-33256.
    PMID: 17895249 DOI: 10.1074/jbc.C700174200
    Curculin isolated from Curculigo latifolia, a plant grown in Malaysia, has an intriguing property of modifying sour taste into sweet taste. In addition to this taste-modifying activity, curculin itself elicits a sweet taste. Although these activities have been attributed to the heterodimeric isoform and not homodimers of curculin, the underlying mechanisms for the dual action of this protein have been largely unknown. To identify critical sites for these activities, we performed a mutational and structural study of recombinant curculin. Based on the comparison of crystal structures of curculin homo- and heterodimers, a series of mutants was designed and subjected to tasting assays. Mapping of amino acid residues on the three-dimensional structure according to their mutational effects revealed that the curculin heterodimer exhibits sweet-tasting and taste-modifying activities through its partially overlapping but distinct molecular surfaces. These findings suggest that the two activities of the curculin heterodimer are expressed through its two different modes of interactions with the T1R2-T1R3 heterodimeric sweet taste receptor.
    Matched MeSH terms: Plant Proteins/physiology*
  18. Fulltext Mechanisms of resistance in nontyphoidal Salmonella enterica strains exhibiting a nonclassical quinolone resistance phenotype
    Gunell M, Webber MA, Kotilainen P, Lilly AJ, Caddick JM, Jalava J, et al.
    Antimicrob Agents Chemother, 2009 Sep;53(9):3832-6.
    PMID: 19596880 DOI: 10.1128/AAC.00121-09
    Nontyphoidal Salmonella enterica strains with a nonclassical quinolone resistance phenotype were isolated from patients returning from Thailand or Malaysia to Finland. A total of 10 isolates of seven serovars were studied in detail, all of which had reduced susceptibility (MIC > or = 0.125 microg/ml) to ciprofloxacin but were either susceptible or showed only low-level resistance (MIC < or = 32 microg/ml) to nalidixic acid. Phenotypic characterization included susceptibility testing by the agar dilution method and investigation of efflux activity. Genotypic characterization included the screening of mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE by PCR and denaturing high-pressure liquid chromatography and the amplification of plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qnrD, aac(6')-Ib-cr, and qepA by PCR. PMQR was confirmed by plasmid analysis, Southern hybridization, and plasmid transfer. No mutations in the QRDRs of gyrA, gyrB, parC, or parE were detected with the exception of a Thr57-Ser substitution within ParC seen in all but the S. enterica serovar Typhimurium strains. The qnrA and qnrS genes were the only PMQR determinants detected. Plasmids carrying qnr alleles were transferable in vitro, and the resistance phenotype was reproducible in Escherichia coli DH5alpha transformants. These data demonstrate the emergence of a highly mobile qnr genotype that, in the absence of mutation within topoisomerase genes, confers the nontypical quinolone resistance phenotype in S. enterica isolates. The qnr resistance mechanism enables bacteria to survive elevated quinolone concentrations, and therefore, strains carrying qnr alleles may be able to expand during fluoroquinolone treatment. This is of concern since nonclassical quinolone resistance is plasmid mediated and therefore mobilizable.
    Matched MeSH terms: Bacterial Proteins/physiology
  19. The emergence of the multi-species NIP1 effector in Rhynchosporium was accompanied by high rates of gene duplications and losses
    Mohd-Assaad N, McDonald BA, Croll D
    Environ Microbiol, 2019 08;21(8):2677-2695.
    PMID: 30838748 DOI: 10.1111/1462-2920.14583
    Plant pathogens secrete effector proteins to manipulate the host and facilitate infection. Cognate hosts trigger strong defence responses upon detection of these effectors. Consequently, pathogens and hosts undergo rapid coevolutionary arms races driven by adaptive evolution of effectors and receptors. Because of their high rate of turnover, most effectors are thought to be species-specific and the evolutionary trajectories are poorly understood. Here, we investigate the necrosis-inducing protein 1 (NIP1) effector in the multihost pathogen genus Rhynchosporium. We retraced the evolutionary history of the NIP1 locus using whole-genome assemblies of 146 strains covering four closely related species. NIP1 orthologues were present in all species but the locus consistently segregated presence-absence polymorphisms suggesting long-term balancing selection. We also identified previously unknown paralogues of NIP1 that were shared among multiple species and showed substantial copy-number variation within R. commune. The NIP1A paralogue was under significant positive selection suggesting that NIP1A is the dominant effector variant coevolving with host immune receptors. Consistent with this prediction, we found that copy number variation at NIP1A had a stronger effect on virulence than NIP1B. Our analyses unravelled the origins and diversification mechanisms of a pathogen effector family shedding light on how pathogens gain adaptive genetic variation.
    Matched MeSH terms: Fungal Proteins/physiology
  20. Fulltext Gene silencing and Polycomb group proteins: an overview of their structure, mechanisms and phylogenetics
    Golbabapour S, Majid NA, Hassandarvish P, Hajrezaie M, Abdulla MA, Hadi AH
    OMICS, 2013 Jun;17(6):283-96.
    PMID: 23692361 DOI: 10.1089/omi.2012.0105
    DNA methylation, histone modifications, and chromatin configuration are crucially important in the regulation of gene expression. Among these epigenetic mechanisms, silencing the expression of certain genes depending on developmental stage and tissue specificity is a key repressive system in genome programming. Polycomb (Pc) proteins play roles in gene silencing through different mechanisms. These proteins act in complexes and govern the histone methylation profiles of a large number of genes that regulate various cellular pathways. This review focuses on two main Pc complexes, Pc repressive complexes 1 and 2, and their phylogenetic relationship, structures, and function. The dynamic roles of these complexes in silencing will be discussed herein, with a focus on the recruitment of Pc complexes to target genes and the key factors involved in their recruitment.
    Matched MeSH terms: Polycomb-Group Proteins/physiology*
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