Displaying publications 61 - 80 of 133 in total

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  1. Fulltext Functional characterization of cytochrome P450 2A6 allelic variants CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22
    Tiong KH, Yiap BC, Tan EL, Ismail R, Ong CE
    Drug Metab. Dispos., 2010 May;38(5):745-51.
    PMID: 20139165 DOI: 10.1124/dmd.109.031054
    Variation in CYP2A6 levels and activity can be attributed to genetic polymorphism and, thus, functional characterization of allelic variants is necessary to define the importance of CYP2A6 polymorphism in humans. The aim of the present study was to investigate the reported alleles CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22, in terms of the functional consequences of their mutations on the enzyme catalytic activity. With use of the wild-type CYP2A6 cDNA as template, site-directed mutagenesis was performed to introduce nucleotide changes encoding K194E substitution in CYP2A6*15, R203S substitution in CYP2A6*16, K476R substitution in CYP2A6*21, and concurrent D158E and L160I substitutions in CYP2A6*22. Upon sequence verification, the CYP2A6 wild-type and mutant constructs were individually coexpressed with NADPH-cytochrome P450 reductase in Escherichia coli. A kinetic study using a coumarin 7-hydroxylase assay indicated that CYP2A6*15 exhibited higher V(max) than the wild type, whereas all mutant constructs, except for variant CYP2A6*16, exhibited higher K(m) values. Analysis of the V(max)/K(m) ratio revealed that all mutants demonstrated 0.85- to 1.05-fold differences from the wild type, with the exception of variant CYP2A6*22, which only portrayed 39% of the wild-type intrinsic clearance. These data suggested that individuals carrying the CYP2A6*22 allele are likely to have lower metabolism of CYP2A6 substrate than individuals expressing CYP2A6*15, CYP2A6*16, CYP2A6*21, and the wild type.
    Matched MeSH terms: Escherichia coli/metabolism
  2. 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: Escherichia coli/metabolism*
  3. Model-aided atpE gene knockout strategy in Escherichia coli for enhanced succinic acid production from glycerol
    Mienda BS, Shamsir MS, Md Illias R
    J Biomol Struct Dyn, 2016 Aug;34(8):1705-16.
    PMID: 26513379 DOI: 10.1080/07391102.2015.1090341
    Succinic acid is an important platform chemical with a variety of applications. Model-guided metabolic engineering strategies in Escherichia coli for strain improvement to increase succinic acid production using glucose and glycerol remain largely unexplored. Herein, we report what are, to our knowledge, the first metabolic knockout of the atpE gene to have increased succinic acid production using both glucose and alternative glycerol carbon sources in E. coli. Guided by a genome-scale metabolic model, we engineered the E. coli host to enhance anaerobic production of succinic acid by deleting the atpE gene, thereby generating additional reducing equivalents by blocking H(+) conduction across the mutant cell membrane. This strategy produced 1.58 and .49 g l(-1) of succinic acid from glycerol and glucose substrate, respectively. This work further elucidates a model-guided and/or system-based metabolic engineering, involving only a single-gene deletion strategy for enhanced succinic acid production in E. coli.
    Matched MeSH terms: Escherichia coli/metabolism*
  4. Negative chromatography purification of hepatitis B virus-like particles using poly(oligo(ethylene glycol) methacrylate) grafted cationic adsorbent
    Lee MF, Chan ES, Tan WS, Tam KC, Tey BT
    J Chromatogr A, 2015 Oct 9;1415:161-5.
    PMID: 26358561 DOI: 10.1016/j.chroma.2015.08.056
    Poly(oligo(ethylene glycol) methacrylate) (POEGMA), an inert polymer was grafted onto an anion exchange adsorbent for the exclusion of relatively larger hepatitis B virus-like particles (HB-VLPs) from the anion exchange ligand (Q) and at the same time this process allowed the selective adsorption of smaller size Escherichia coli host cell proteins (HCPs). The chain lengths of the POEGMA grafted were modulated by varying the amount of monomers used in the polymer grafting. The purification factor and yield of the HB-VLPs obtained from the flow-through of negative chromatography were 2.3 and 66.0±3.1%, respectively, when shorter chain length of POEGMA (SQ) was grafted. Adsorbent grafted with longer chain of POEGMA (LQ) excluded some HCPs that are larger in size together with the HB-VLPs, reducing the purity of the recovered HB-VLPs. Further heat-treatment of the flow-through pool from SQ followed by centrifugation increased the purity of heat stable HB-VLPs to 87.5±1.1%. Heat-treatment of the flow through sample resulted in thermal denaturation and aggregation of HCPs, while the heat stable HB-VLPs still remained intact as observed under a transmission electron microscope. The performance of the negative chromatography together with heat treatment in the purification of HB-VLPs is far better than the reported bind-and-elute techniques.
    Matched MeSH terms: Escherichia coli/metabolism
  5. Production of the virus-like particles of nipah virus matrix protein in Pichia pastoris as diagnostic reagents
    Joseph NM, Ho KL, Tey BT, Tan CS, Shafee N, Tan WS
    Biotechnol Prog, 2016 Jul 08;32(4):1038-45.
    PMID: 27088434 DOI: 10.1002/btpr.2279
    The matrix (M) protein of Nipah virus (NiV) is a peripheral protein that plays a vital role in the envelopment of nucleocapsid protein and acts as a bridge between the viral surface and the nucleocapsid proteins. The M protein is also proven to play an important role in production of virus-like particles (VLPs) and is essential for assembly and budding of NiV particles. The recombinant M protein produced in Escherichia coli assembled into VLPs in the absence of the viral surface proteins. However, the E. coli produced VLPs are smaller than the native virus particles. Therefore, the aims of this study were to produce NiV M protein in Pichia pastoris, to examine the structure of the VLPs formed, and to assess the potential of the VLPs as a diagnostic reagent. The M protein was successfully expressed in P. pastoris and was detected with anti-myc antibody using Western blotting. The VLPs formed by the recombinant M protein were purified with sucrose density gradient ultracentrifugation, high-performance liquid chromatography (HPLC), and Immobilized Metal Affinity Chromatography (IMAC). Immunogold staining and transmission electron microscopy confirmed that the M protein assembled into VLPs as large as 200 nm. ELISA revealed that the NiV M protein produced in P. pastoris reacted strongly with positive NiV sera demonstrating its potential as a diagnostic reagent. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1038-1045, 2016.
    Matched MeSH terms: Escherichia coli/metabolism
  6. Detection of human malaria using recombinant Plasmodium knowlesi merozoire surface protein-1 (MSP-1₁₉) expressed in Escherichia coli
    Sonaimuthu P, Cheong FW, Chin LC, Mahmud R, Fong MY, Lau YL
    Exp Parasitol, 2015 Jun;153:118-22.
    PMID: 25812552 DOI: 10.1016/j.exppara.2015.03.010
    Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Human infection with Plasmodium knowlesi is widely distributed in Southeast Asia. Merozoite surface protein-1₁₉ (MSP-1₁₉), which plays an important role in protective immunity against asexual blood stage malaria parasites, appears as a leading immunogenic antigen of Plasmodium sp. We evaluated the sensitivity and specificity of recombinant P. knowlesi MSP-1₁₉ (rMSP-1₁₉) for detection of malarial infection. rMSP-1₁₉ was expressed in Escherichia coli expression system and the purified rMSP-1₁₉ was evaluated with malaria, non-malaria and healthy human serum samples (n = 215) in immunoblots. The sensitivity of rMSP-1₁₉ for detection of P. knowlesi, Plasmodium falciparum, Plasmodium  vivax and Plasmodium  ovale infection was 95.5%, 75.0%, 85.7% and 100%, respectively. rMSP-1₁₉ did not react with all the non-malaria and healthy donor sera, which represents 100% specificity. The rMSP-1₁₉ could be used as a potential antigen in serodiagnosis of malarial infection in humans.
    Matched MeSH terms: Escherichia coli/metabolism
  7. Fulltext Comparison of methods in the detection of enterotoxigenic Escherichia coli in a Malaysian laboratory
    Cheong YM, Jegathesan M, Ansary A, Othman M
    Med J Malaysia, 1990 Mar;45(1):42-8.
    PMID: 2152068
    The prevalence of Enterotoxigenic Escherichia coli (ETEC) in 433 stool samples from diarrhoeal cases of all ages was studied using two commercially available test kits for the detection of heat labile toxin (LT) and the infant mouse assay for the heat stable toxin (ST). 16 samples (3.7%) were positive for ETEC, of which nine were producing ST alone, six LT alone and only one was producing both LT and ST. Although the percentage of isolation rate was low, its occurrence was almost as common as the Shigella spp and Salmonella spp in the same study. Of the two test kits examined, the Phadebact ETEC-LT Test 50 (Pharmacia Diagnostics, Uppsala, Sweden) was found to be more suitable for use in a routine diagnostic laboratory. Ten out of 12 (83%) of the strains tested were resistant to one or more antibiotics.
    Matched MeSH terms: Escherichia coli/metabolism
  8. A new cold-adapted, organic solvent stable lipase from mesophilic Staphylococcus epidermidis AT2
    Kamarudin NH, Rahman RN, Ali MS, Leow TC, Basri M, Salleh AB
    Protein J, 2014 Jun;33(3):296-307.
    PMID: 24777627 DOI: 10.1007/s10930-014-9560-3
    The gene encoding a cold-adapted, organic solvent stable lipase from a local soil-isolate, mesophilic Staphylococcus epidermidis AT2 was expressed in a prokaryotic system. A two-step purification of AT2 lipase was achieved using butyl sepharose and DEAE sepharose column chromatography. The final recovery and purification fold were 47.09 % and 3.45, respectively. The molecular mass of the purified lipase was estimated to be 43 kDa. AT2 lipase was found to be optimally active at pH 8 and stable at pH 6-9. Interestingly, this enzyme demonstrated remarkable stability at cold temperature (<30 °C) and exhibited optimal activity at a temperature of 25 °C. A significant enhancement of the lipolytic activity was observed in the presence of Ca(2+), Tween 60 and Tween 80. Phenylmethylsulfonylfluoride, a well known serine inhibitor did not cause complete inhibition of the enzymatic activity. AT2 lipase exhibited excellent preferences towards long chain triglycerides and natural oils. The lipolytic activity was stimulated by dimethylsulfoxide and diethyl ether, while more than 50 % of its activity was retained in methanol, ethanol, acetone, toluene, and n-hexane. Taken together, AT2 lipase revealed highly attractive biochemical properties especially because of its stability at low temperature and in organic solvents.
    Matched MeSH terms: Escherichia coli/metabolism
  9. Site-saturation mutagenesis of mutant L-asparaginase II signal peptide hydrophobic region for improved excretion of cyclodextrin glucanotransferase
    Ismail A, Illias RM
    J Ind Microbiol Biotechnol, 2017 Dec;44(12):1627-1641.
    PMID: 28921081 DOI: 10.1007/s10295-017-1980-6
    The excretion of cyclodextrin glucanotransferase (CGTase) into the culture medium offers significant advantages over cytoplasmic expression. However, the limitation of Escherichia coli is its inability to excrete high amount of CGTase outside the cells. In this study, modification of the hydrophobic region of the N1R3 signal peptide using site-saturation mutagenesis improved the excretion of CGTase. Signal peptide mutants designated M9F, V10L and A15Y enhanced the excretion of CGTase three-fold and demonstrated two-fold higher secretion rate than the wild type. However, high secretion rate of these mutants was non-productive for recombinant protein production because it caused up to a seven-fold increase in cell death compared to the wild type. Our results indicated that the excretion of CGTase is highly dependent on hydrophobicity, secondary conformation and the type and position of amino acids at the region boundary and core segment of the h-region.
    Matched MeSH terms: Escherichia coli/metabolism
  10. Fulltext New Recombinant Cold-Adapted and Organic Solvent Tolerant Lipase from Psychrophilic Pseudomonas sp. LSK25, Isolated from Signy Island Antarctica
    Salwoom L, Raja Abd Rahman RNZ, Salleh AB, Mohd Shariff F, Convey P, Mohamad Ali MS
    Int J Mol Sci, 2019 Mar 13;20(6).
    PMID: 30871178 DOI: 10.3390/ijms20061264
    In recent years, studies on psychrophilic lipases have become an emerging area of research in the field of enzymology. The study described here focuses on the cold-adapted organic solvent tolerant lipase strain Pseudomonas sp. LSK25 isolated from Signy Station, South Orkney Islands, maritime Antarctic. Strain LSK25 lipase was successfully cloned, sequenced, and over-expressed in an Escherichia coli system. Sequence analysis revealed that the lipase gene of Pseudomonas sp. LSK25 consists of 1432 bp, lacks an N-terminal signal peptide and encodes a mature protein consisting of 476 amino acids. The recombinant LSK25 lipase was purified by single-step purification using Ni-Sepharose affinity chromatography and had a molecular mass of approximately 65 kDa. The final recovery and purification fold were 44% and 1.3, respectively. The LSK25 lipase was optimally active at 30 °C and at pH 6. Stable lipolytic activity was reported between temperatures of 5⁻30 °C and at pH 6⁻8. A significant enhancement of lipolytic activity was observed in the presence of Ca2+ ions, the organic lipids of rice bran oil and coconut oil, a synthetic C12 ester and a wide range of water immiscible organic solvents. Overall, lipase strain LSK25 is a potentially desirable candidate for biotechnological application, due to its stability at low temperatures, across a range of pH and in organic solvents.
    Matched MeSH terms: Escherichia coli/metabolism
  11. Fulltext Effects of feeding and induction strategy on the production of BmR1 antigen in recombinant E. coli
    Norsyahida A, Rahmah N, Ahmad RM
    Lett Appl Microbiol, 2009 Nov;49(5):544-50.
    PMID: 19832937 DOI: 10.1111/j.1472-765X.2009.02694.x
    To investigate the effects of feeding and induction strategies on the production of BmR1 recombinant antigen.
    Matched MeSH terms: Escherichia coli/metabolism*
  12. Application of the linear interaction energy method (LIE) to estimate the binding free energy values of Escherichia coli wild-type and mutant arginine repressor C-terminal domain (ArgRc)-l-arginine and ArgRc-l-citrulline protein-ligand complexes
    Asi AM, Rahman NA, Merican AF
    J Mol Graph Model, 2004 Mar;22(4):249-62.
    PMID: 15177077
    Protein-ligand binding free energy values of wild-type and mutant C-terminal domain of Escherichia coli arginine repressor (ArgRc) protein systems bound to L-arginine or L-citrulline molecules were calculated using the linear interaction energy (LIE) method by molecular dynamics (MD) simulation. The binding behaviour predicted by the dissociation constant (K(d)) calculations from the binding free energy values showed preferences for binding of L-arginine to the wild-type ArgRc but not to the mutant ArgRc(D128N). On the other hand, L-citrulline do not favour binding to wild-type ArgRc but prefer binding to mutant ArgRc(D128N). The dissociation constant for the wild-type ArgRc-L-arginine complex obtained in this study is in agreement with reported experimental results. Our results also support the experimental data for the binding of L-citrulline to the mutant ArgRc(D128N). These showed that LIE method for protein-ligand binding free energy calculation could be applied to the wild-type and the mutant E. coli ArgRc-L-arginine and ArgRc-L-citrulline protein-ligand complexes and possibly to other transcriptional repressor-co-repressor systems as well.
    Matched MeSH terms: Escherichia coli/metabolism
  13. Fulltext Microtiter miniature shaken bioreactor system as a scale-down model for process development of production of therapeutic alpha-interferon2b by recombinant Escherichia coli
    Tan JS, Abbasiliasi S, Kadkhodaei S, Tam YJ, Tang TK, Lee YY, et al.
    BMC Microbiol, 2018 01 04;18(1):3.
    PMID: 29439680 DOI: 10.1186/s12866-017-1145-9
    BACKGROUND: Demand for high-throughput bioprocessing has dramatically increased especially in the biopharmaceutical industry because the technologies are of vital importance to process optimization and media development. This can be efficiently boosted by using microtiter plate (MTP) cultivation setup embedded into an automated liquid-handling system. The objective of this study was to establish an automated microscale method for upstream and downstream bioprocessing of α-IFN2b production by recombinant Escherichia coli. The extraction performance of α-IFN2b by osmotic shock using two different systems, automated microscale platform and manual extraction in MTP was compared.

    RESULTS: The amount of α-IFN2b extracted using automated microscale platform (49.2 μg/L) was comparable to manual osmotic shock method (48.8 μg/L), but the standard deviation was 2 times lower as compared to manual osmotic shock method. Fermentation parameters in MTP involving inoculum size, agitation speed, working volume and induction profiling revealed that the fermentation conditions for the highest production of α-IFN2b (85.5 μg/L) was attained at inoculum size of 8%, working volume of 40% and agitation speed of 1000 rpm with induction at 4 h after the inoculation.

    CONCLUSION: Although the findings at MTP scale did not show perfect scalable results as compared to shake flask culture, but microscale technique development would serve as a convenient and low-cost solution in process optimization for recombinant protein.

    Matched MeSH terms: Escherichia coli/metabolism*
  14. Fulltext Recovery of recombinant Mycobacterium tuberculosis antigens fused with cell wall-anchoring motif (LysM) from inclusion bodies using non-denaturing reagent (N-laurylsarcosine)
    Mustafa AD, Kalyanasundram J, Sabidi S, Song AA, Abdullah M, Abdul Rahim R, et al.
    BMC Biotechnol, 2019 05 14;19(1):27.
    PMID: 31088425 DOI: 10.1186/s12896-019-0522-x
    BACKGROUND: The current limitations of conventional BCG vaccines highlights the importance in developing novel and effective vaccines against tuberculosis (TB). The utilization of probiotics such as Lactobacillus plantarum for the delivery of TB antigens through in-trans surface display provides an effective and safe vaccine approach against TB. Such non-recombinant probiotic surface display strategy involves the fusion of candidate proteins with cell wall binding domain such as LysM, which enables the fusion protein to anchor the L. plantarum cell wall externally, without the need for vector genetic modification. This approach requires sufficient production of these recombinant fusion proteins in cell factory such as Escherichia coli which has been shown to be effective in heterologous protein production for decades. However, overexpression in E. coli expression system resulted in limited amount of soluble heterologous TB-LysM fusion protein, since most of it are accumulated as insoluble aggregates in inclusion bodies (IBs). Conventional methods of denaturation and renaturation for solubilizing IBs are costly, time-consuming and tedious. Thus, in this study, an alternative method for TB antigen-LysM protein solubilization from IBs based on the use of non-denaturating reagent N-lauroylsarcosine (NLS) was investigated.

    RESULTS: Expression of TB antigen-LysM fusion genes was conducted in Escherichia coli, but this resulted in IBs deposition in contrast to the expression of TB antigens only. This suggested that LysM fusion significantly altered solubility of the TB antigens produced in E. coli. The non-denaturing NLS technique was used and optimized to successfully solubilize and purify ~ 55% of the recombinant cell wall-anchoring TB antigen from the IBs. Functionality of the recovered protein was analyzed via immunofluorescence microscopy and whole cell ELISA which showed successful and stable cell wall binding to L. plantarum (up to 5 days).

    CONCLUSION: The presented NLS purification strategy enables an efficient and rapid method for obtaining higher yields of soluble cell wall-anchoring Mycobacterium tuberculosis antigens-LysM fusion proteins from IBs in E. coli.

    Matched MeSH terms: Escherichia coli/metabolism
  15. Fulltext Production and purification of polymerization-competent HIV-1 capsid protein p24 (CA) in NiCo21(DE3) Escherichia coli
    Teow SY, Mualif SA, Omar TC, Wei CY, Yusoff NM, Ali SA
    BMC Biotechnol, 2013;13:107.
    PMID: 24304876 DOI: 10.1186/1472-6750-13-107
    HIV genome is packaged and organized in a conical capsid, which is made up of ~1,500 copies of the viral capsid protein p24 (CA). Being a primary structural component and due to its critical roles in both late and early stages of the HIV replication cycle, CA has attracted increased interest as a drug discovery target in recent years. Drug discovery studies require large amounts of highly pure and biologically active protein. It is therefore desirable to establish a simple and reproducible process for efficient production of HIV-1 CA.
    Matched MeSH terms: Escherichia coli/metabolism
  16. Functional and structural analyses of an expansin-like protein from the antarctic yeast Glaciozyma antarctica PI12 reveal strategies of nutrient scavenging in the sea ice environment
    Mohamad Nor N, Hashim NHF, Quay DHX, Mahadi NM, Illias RM, Abu Bakar FD, et al.
    Int J Biol Macromol, 2020 Feb 01;144:231-241.
    PMID: 31843615 DOI: 10.1016/j.ijbiomac.2019.12.099
    Genome data mining of the Antarctic yeast, Glaciozyma antarctica PI12 revealed an expansin-like protein encoding sequence (GaEXLX1). The GaEXLX1 protein is 24.8 kDa with a high alkaline pI of 9.81. Homology modeling of GaEXLX1 showed complete D1 and D2 domains of a conventional expansin. The protein exhibited 36% sequence similarity to Clavibacter michiganensis EXLX1 (PDB: 4JCW). Subsequently, a recombinant GaEXLX1 protein was produced using Escherichia coli expression system. Incubation with Avicel, filter paper and cotton fiber showed that the protein can disrupt the surface of crystalline and pure cellulose, suggesting a cell wall modification activity usually exhibited by expansin-like proteins. Binding assays displayed that GaEXLX1 can bind to polymeric substrates, including those postulated to be present in the sea ice ecosystem such as crab chitin and moss lichenan. GaEXLX1 may assist in the recognition and loosening of these substrates in the sea ice prior to hydrolysis by other extracellular enzymes. Similar loosening mechanism to classical expansin-like protein has been postulated for this psychrophilic protein based on several conserved residues of GaEXLX1 involved in binding interaction identified by docking analyses.
    Matched MeSH terms: Escherichia coli/metabolism
  17. Heterologous expression of the tetracycline resistance gene tetX to enhance degradability and safety in doxycycline degradation
    Wen X, Huang J, Cao J, Xu J, Mi J, Wang Y, et al.
    Ecotoxicol Environ Saf, 2020 Mar 15;191:110214.
    PMID: 31968275 DOI: 10.1016/j.ecoenv.2020.110214
    Microbial remediation has the potential to inexpensively yet effectively decontaminate and restore contaminated environments, but the virulence of pathogens and risk of resistance gene transmission by microorganisms during antibiotic removal often limit its implementation. Here, a cloned tetX gene with clear evolutionary history was expressed to explore doxycycline (DOX) degradation and resistance variation during the degradation process. Phylogenetic analysis of tetX genes showed high similarity with those of pathogenic bacteria, such as Riemerella sp. and Acinetobacter sp. Successful tetX expression was performed in Escherichia coli and confirmed by SDS-PAGE and Western blot. Our results showed that 95.0 ± 1.0% of the DOX (50 mg/L) was degraded by the recombinant strain (ETD-1 with tetX) within 48 h, which was significantly higher than that for the control (38.9 ± 8.7%) and the empty plasmid bacteria (8.8 ± 5.1%) (P  0.05). The efficient and safe DOX-degrading capacity of the recombinant strain ETD-1 makes it valuable and promising for antibiotic removal in the environment.
    Matched MeSH terms: Escherichia coli/metabolism
  18. Fulltext AidP, a novel N-Acyl homoserine lactonase gene from Antarctic Planococcus sp
    See-Too WS, Ee R, Lim YL, Convey P, Pearce DA, Yin WF, et al.
    Sci Rep, 2017 02 22;7:42968.
    PMID: 28225085 DOI: 10.1038/srep42968
    Planococcus is a Gram-positive halotolerant bacterial genus in the phylum Firmicutes, commonly found in various habitats in Antarctica. Quorum quenching (QQ) is the disruption of bacterial cell-to-cell communication (known as quorum sensing), which has previously been described in mesophilic bacteria. This study demonstrated the QQ activity of a psychrotolerant strain, Planococcus versutus strain L10.15T, isolated from a soil sample obtained near an elephant seal wallow in Antarctica. Whole genome analysis of this bacterial strain revealed the presence of an N-acyl homoserine lactonase, an enzyme that hydrolyzes the ester bond of the homoserine lactone of N-acyl homoserine lactone (AHLs). Heterologous gene expression in E. coli confirmed its functions for hydrolysis of AHLs, and the gene was designated as aidP (autoinducer degrading gene from Planococcus sp.). The low temperature activity of this enzyme suggested that it is a novel and uncharacterized class of AHL lactonase. This study is the first report on QQ activity of bacteria isolated from the polar regions.
    Matched MeSH terms: Escherichia coli/metabolism
  19. Purification of histidine-tagged nucleocapsid protein of Nipah virus using immobilized metal affinity chromatography
    Chong FC, Tan WS, Biak DR, Ling TC, Tey BT
    J Chromatogr B Analyt Technol Biomed Life Sci, 2009 May 15;877(14-15):1561-7.
    PMID: 19395325 DOI: 10.1016/j.jchromb.2009.03.048
    Nucleocapsid (N) protein of Nipah virus (NiV) is a potential serological marker used in the diagnosis of NiV infections. In this study, a rapid and efficient purification system, HisTrap 6 Fast Flow packed bed column was applied to purify recombinant histidine-tagged N protein of NiV from clarified feedstock. The optimizations of binding and elution conditions of N protein of NiV onto and from Nickel Sepharose 6 Fast Flow were investigated. The optimal binding was achieved at pH 7.5, superficial velocity of 1.25 cm/min. The bound N protein was successfully recovered by a stepwise elution with different concentration of imidazole (50, 150, 300 and 500 mM). The N protein of NiV was captured and eluted from an inlet N protein concentration of 0.4 mg/ml in a scale-up immobilized metal affinity chromatography (IMAC) packed bed column of Nickel Sepharose 6 Fast Flow with the optimized condition obtained from the method scouting. The purification of histidine-tagged N protein using IMAC packed bed column has resulted a 68.3% yield and a purification factor of 7.94.
    Matched MeSH terms: Escherichia coli/metabolism
  20. Fulltext Thermotolerance and molecular chaperone function of an SGT1-like protein from the psychrophilic yeast, Glaciozyma antarctica
    Yusof NA, Hashim NH, Beddoe T, Mahadi NM, Illias RM, Bakar FD, et al.
    Cell Stress Chaperones, 2016 Jul;21(4):707-15.
    PMID: 27154490 DOI: 10.1007/s12192-016-0696-2
    The ability of eukaryotes to adapt to an extreme range of temperatures is critically important for survival. Although adaptation to extreme high temperatures is well understood, reflecting the action of molecular chaperones, it is unclear whether these molecules play a role in survival at extremely low temperatures. The recent genome sequencing of the yeast Glaciozyma antarctica, isolated from Antarctic sea ice near Casey Station, provides an opportunity to investigate the role of molecular chaperones in adaptation to cold temperatures. We isolated a G. antarctica homologue of small heat shock protein 20 (HSP20), GaSGT1, and observed that the GaSGT1 mRNA expression in G. antarctica was markedly increased following culture exposure at low temperatures. Additionally, we demonstrated that GaSGT1 overexpression in Escherichia coli protected these bacteria from exposure to both high and low temperatures, which are lethal for growth. The recombinant GaSGT1 retained up to 60 % of its native luciferase activity after exposure to luciferase-denaturing temperatures. These results suggest that GaSGT1 promotes cell thermotolerance and employs molecular chaperone-like activity toward temperature assaults.
    Matched MeSH terms: Escherichia coli/metabolism
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