Displaying publications 21 - 40 of 87 in total

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  1. Fulltext Rare Elizabethkingia anophelis meningitis case in a Danish male
    Nielsen HL, Tarpgaard IH, Fuglsang-Damgaard D, Thomsen PK, Brisse S, Dalager-Pedersen M
    JMM Case Rep, 2018 Aug;5(8):e005163.
    PMID: 30323938 DOI: 10.1099/jmmcr.0.005163
    Introduction: Elizabethkingia anophelis is a Gram-negative, aerobic, non-motile rod belonging to the family Flavobacteriaceae. Over the last 5 years, it has emerged as an opportunistic human pathogen involved in neonatal meningitis and sepsis, as well as nosocomial outbreaks. It has been isolated from the midgut of the Anopheles gambiae mosquito, but there is no evidence for a role of the mosquito in human infections, and very little is known regarding the routes of transmission to humans. Recent studies, primarily from South-East Asia, suggest that E. anophelis, and not Elizabethkingia meningoseptica, is the predominant human pathogen of this genus. However, identification to the species level has been difficult due to the limitations of the current MALDI-TOF MS (matrix-associated laser desorption ionization-time of flight MS) systems for correct species identification.

    Case presentation: Here, we present a rare case of E. anophelis meningitis in a Danish male, who had a travel exposure to Malaysia 7 weeks before hospitalization. A multidrug-resistant Elizabethkingia species was isolated from blood and cerebrospinal fluid, and genomic sequencing was used to characterize the phylogenetic position of the isolate, which was determined as associated with previously described sublineage 11. The patient was successfully treated with intravenous moxifloxacin and rifampicin for 2 weeks with no major sequelae, but we did not find the source of transmission.

    Conclusion: All clinical microbiologists should be aware of the present limitations of the MALDI-TOF MS systems for correct species identification, and therefore we recommend the use of genome sequencing for the correct identification at the species and sublineage level.

    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  2. Fulltext Differences in thermostable actin profile of goat meat as observed in twodimensional gel electrophoresis (2DE)
    Sarah, S.A., Amin, I., Mokhtar, N.F.K., Sazili, A.Q., Karsani S.A.
    International Food Research Journal, 2013;20(2):897-901.
    MyJurnal
    Different heat treatments, (1) chilled, 4°C (2) boiled at 100°C for 30 min and (3) autoclaved at 121°C at 15 psi for 20 min were employed on goat meat to mimic domestic and industrial cooking. The effects on intensity of actin proteins was observed using two-dimensional gel electrophoresis where significant differences (p>0.05) were observed in the spot intensity between chilled and boiled samples, similarly in chilled and autoclaved samples. However, no significant difference was observed between boiled and autoclaved samples. The slight changes observed in the cooking of meat confirmed that actin protein is susceptible to denaturation cause by heat. MALDI-TOF/TOF analysis revealed the peptide-mass fingerprint between positions 21 – 374 that not affected by heat treatment. Peptides from this position merit the candidature of actin as putative thermostable marker for detecting goat meat (chevon) in food product.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  3. Septicaemia due to Vibrio vulnificus: A tropical infection not to be taken lightly
    Ding CH, Wahab WA, Saaid MS, Mokhtar MN, Abdullah FA, Azaharuddin I
    Trop Biomed, 2024 Jun 01;41(2):157-159.
    PMID: 39154267 DOI: 10.47665/tb.41.2.004
    Vibrio vulnificus is a halophilic gram-negative bacillus that can cause fulminant septicaemia in immunocompromised patients. A 67-year-old man who was immunosuppressed as a result of cytotoxic chemotherapy presented with a brief history of fever, lethargy, myalgia, and reduced oral intake. He had recently travelled to the beach to consume seafood. His blood pressure was 81/47 mm Hg, necessitating fluid resuscitation followed by inotropic support and admission to the intensive care unit. His blood culture was positive for curved gram-negative bacilli. The isolate was oxidase-positive and produced an acid butt with an alkaline slant in triple sugar iron agar. Matrix-assisted laser desorption ionization-time of flight mass spectrometry conclusively identified the isolate as V. vulnificus. Intravenous ceftazidime plus ciprofloxacin were administered, and by the fifth day of admission, he was successfully transferred out to the general ward. In total, the patient completed a 14-day course of antibiotic therapy.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  4. Proteomics technology - a powerful tool for the biomedical scientists
    Noordin R, Othman N
    Malays J Med Sci, 2013 Mar;20(2):1-2.
    PMID: 23983570
    "Proteomics" refers to the systematic analysis of proteins. It complements other "omics" technologies such as genomics and transcriptomics in elucidating the identity of proteins of an organism, and understanding their functions. Proteomics is used in many areas of research such as discovery of markers for diagnosis and vaccine candidates, understanding pathogenic mechanisms, in the study of expression patterns at different time points and in response to different stimuli, and in elucidating functional protein networks. Proteomics analysis involves sample preparation, protein separation, and protein identification. The 'heart' of current proteomics is mass-spectrometry, with LC-MS/MS and MALDI-TOF/TOF being commonly used equipment. However, the high costs of the equipment, software, databases, and the need for skilled personnel limit the wide utilization of this technology in the less developed countries. Therefore, there need to be sharing of facilities, better networking and collaborations among our scientists and laboratories to take advantage of this powerful technology.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  5. Bacteremia due to the fastidious bacterium Granulicatella adiacens: A diagnosis that was almost missed
    Ding CH, Wahab AA, Mohamed N, Wong PF
    Trop Biomed, 2025 Mar 01;42(1):58-60.
    PMID: 40163405 DOI: 10.47665/tb.42.1.010
    Bacteremia due to Granulicatella adiacens has been rarely reported in the medical literature. A middleaged gentleman developed necrotizing fasciitis on his left second toe after stepping on a nail. A ray amputation was performed and ceftazidime-susceptible Pseudomonas aeruginosa was isolated from his bone culture. However, while receiving ceftazidime for the necrotizing fasciitis, his blood culture vial was positive for gram-positive cocci-shaped bacteria in short chains which grew as tiny non-lytic colonies on sheep blood agar only following extended incubation. There was no culture evidence of P. aeruginosa in the same blood specimen. The gram-positive organism was conclusively identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry as G. adiacens. The patient was treated with benzylpenicillin (to which the organism tested susceptible) for 14 days before he was discharged home.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  6. Fulltext Characterisation of potential antidiabetic-related proteins from Pleurotus pulmonarius (Fr.) Quél. (grey oyster mushroom) by MALDI-TOF/TOF mass spectrometry
    Wahab NA, Abdullah N, Aminudin N
    Biomed Res Int, 2014;2014:131607.
    PMID: 25243114 DOI: 10.1155/2014/131607
    Pleurotus pulmonarius has been reported to have a potent remedial effect on diabetic property and considered to be an alternative for type 2 diabetes mellitus treatment. This study aimed to investigate the antidiabetic properties of ammonium sulphate precipitated protein fractions from P. pulmonarius basidiocarps. Preliminary results demonstrated that 30% (NH4)2SO4 precipitated fraction (F30) inhibited Saccharomyces cerevisiae α-glucosidase activity (24.18%), and 100% (NH4)2SO4 precipitated fraction (F100) inhibited porcine pancreatic α-amylase activity (41.80%). Following RP-HPLC purification, peak 3 from F30 fraction demonstrated inhibition towards α-glucosidase at the same time with meagre inhibition towards α-amylase activity. Characterisation of proteins using MALDI-TOF/TOF MS demonstrated the presence of four different proteins, which could be implicated in the regulation of blood glucose level via various mechanisms. Therefore, this study revealed the presence of four antidiabetic-related proteins which are profilin-like protein, glyceraldehyde-3-phosphate dehydrogenase-like protein, trehalose phosphorylase-like (TP-like) protein, and catalase-like protein. Hence, P. pulmonarius basidiocarps have high potential in lowering blood glucose level, reducing insulin resistance and vascular complications.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  7. Comparative SELDI-TOF-MS profiling of low-molecular-mass proteins from Lignosus rhinocerus (Cooke) Ryvarden grown under stirred and static conditions of liquid fermentation
    Lau BF, Aminudin N, Abdullah N
    J Microbiol Methods, 2011 Oct;87(1):56-63.
    PMID: 21801760 DOI: 10.1016/j.mimet.2011.07.005
    Mushrooms are considered as important source of biologically active compounds which include low-molecular-mass protein/peptides (LMMP). In this study, we attempted to profile the LMMP from Lignosus rhinocerus, a wild medicinal mushroom, grown by static cultures (SC) and in stirred tank reactor (STR). Crude water extract (CWE) and protein fractions were profiled using H50 ProteinChip® arrays and SELDI-TOF-MS. Three protein peaks of 5.8, 6.9 and 9.1 kDa were found to be common to spectra of L. rhinocerus CWE from both culture conditions. Partial protein purification has resulted in detection of more peaks in the spectra of protein fractions. For protein fractions of L. rhinocerus cultured in STR, most peaks were observed in the range of 3-8 kDa whereas some peaks with molecular mass up to 14.3 kDa were noted in spectra of protein fractions from SC. Our results have demonstrated the optimization of profiling method using SELDI-TOF-MS for fungal LMMP.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*
  8. Lymph node metastasis of primary endometrial cancers: Associated proteins revealed by MALDI imaging
    Mittal P, Klingler-Hoffmann M, Arentz G, Winderbaum L, Lokman NA, Zhang C, et al.
    Proteomics, 2016 06;16(11-12):1793-801.
    PMID: 27061135 DOI: 10.1002/pmic.201500455
    Metastasis is a crucial step of malignant progression and is the primary cause of death from endometrial cancer. However, clinicians presently face the challenge that conventional surgical-pathological variables, such as tumour size, depth of myometrial invasion, histological grade, lymphovascular space invasion or radiological imaging are unable to predict with accuracy if the primary tumour has metastasized. In the current retrospective study, we have used primary tumour samples of endometrial cancer patients diagnosed with (n = 16) and without (n = 27) lymph node metastasis to identify potential discriminators. Using peptide matrix assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI), we have identified m/z values which can classify 88% of all tumours correctly. The top discriminative m/z values were identified using a combination of in situ sequencing and LC-MS/MS from digested tumour samples. Two of the proteins identified, plectin and α-Actin-2, were used for validation studies using LC-MS/MS data independent analysis (DIA) and immunohistochemistry. In summary, MALDI-MSI has the potential to identify discriminators of metastasis using primary tumour samples.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  9. Proteomic Analysis of Synovial Fluid Obtained From a Dog Diagnosed With Idiopathic Immune-Mediated Polyarthritis
    Tan WM, Lau SF, Ajat M, Mansor R, Abd Rani PAM, Rahmad NB
    Top Companion Anim Med, 2017 Mar;32(1):24-27.
    PMID: 28750786 DOI: 10.1053/j.tcam.2017.05.002
    This case study is to report the proteins detected by proteomic analysis of synovial fluid from a dog diagnosed with idiopathic immune-mediated polyarthritis, and to compare it with healthy dogs. Synovial fluid was collected via arthrocentesis from a dog diagnosed with immune-mediated polyarthritis. Protein precipitation was performed on the synovial fluid, followed by isoelectric focusing and 2-dimensional gel electrophoresis. The spots on the 2-dimensional gels were analyzed using MALDI-TOF/MS. The results were then analyzed against the MASCOT database. The results from the proteomic analysis revealed an abundance of several types of immunoglobulins together with the presence of complement C4b-binding protein alpha chain. Actin and keratin were also among the proteins detected. Proteomic studies, facilitate a better understanding of the different levels of proteins expressed during disease activity. Potential disease biomarkers can aid in the diagnosis of disease, as well as help in monitoring treatment efficacy and providing prognosis for the patient.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/veterinary
  10. A MALDI TOF MS-based minisequencing method for rapid detection of TEM-type extended-spectrum beta-lactamases in clinical strains of Enterobacteriaceae
    Ikryannikova LN, Shitikov EA, Zhivankova DG, Il'ina EN, Edelstein MV, Govorun VM
    J Microbiol Methods, 2008 Dec;75(3):385-91.
    PMID: 18694787 DOI: 10.1016/j.mimet.2008.07.005
    A minisequencing method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) was developed for rapid identification of single nucleotide polymorphisms at bla(TEM) gene codons 104, 164 and 238 associated with extended-spectrum activity on TEM-type beta-lactamases. The method was validated by testing the Escherichia coli and Klebsiella pneumoniae strains possessing the known bla(TEM) gene sequences.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  11. Identification of a 48kDa tubulin or tubulin-like C6/36 mosquito cells protein that binds dengue virus 2 using mass spectrometry
    Chee HY, AbuBakar S
    Biochem Biophys Res Commun, 2004 Jul 16;320(1):11-7.
    PMID: 15207695
    Binding of dengue virus 2 (DENV-2) to C6/36 mosquito cells protein was investigated. A 48 kDa DENV-2-binding C6/36 cells protein (D2BP) was detected in a virus overlay protein-binding assay. The binding occurred only to the C6/36 cells cytosolic protein fraction and it was inhibited by free D2BP. D2BP was shown to bind to DENV-2 E in the far-Western-binding studies and using mass spectrometry (MS) and MS/MS, peptide masses of the D2BP that matched to beta-tubulin and alpha-tubulin chains were identified. These findings suggest that DENV-2 through DENV-2 E binds directly to a 48 kDa tubulin or tubulin-like protein of C6/36 mosquito cells.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  12. Proteomic analysis reveals that treatment with tocotrienols reverses the effect of H₂O₂ exposure on peroxiredoxin expression in human lymphocytes from young and old individuals
    Dahlan HM, Karsani SA, Rahman MA, Hamid NA, Top AG, Ngah WZ
    J Nutr Biochem, 2012 Jul;23(7):741-51.
    PMID: 21840697 DOI: 10.1016/j.jnutbio.2011.03.018
    Vitamin E has been suggested to modulate age-associated changes by altering the redox balance resulting in altered gene and/or protein expression. Here we have utilized proteomics to determine whether such regulation in protein expression occurs in human lymphocytes from two different age groups stressed with H₂O₂ and then treated with vitamin E in the form of tocotrienol-rich fraction (TRF). In this study, lymphocytes obtained from young (30-49 years old) and old (>50 years old) volunteers were first challenged with 1 mM H₂O₂. They were then treated by exposure to 50, 100 and 200 μg/ml TRF. Two-dimensional gel electrophoresis followed by MALDI-TOF/TOF (matrix-assisted laser desorption/ionization time-of-flight/time-of-flight) tandem mass spectrometry was then performed on whole-cell protein extracts to identify proteins that have changed in expression. A total of 24 proteins were found to be affected by H₂O₂ and/or TRF treatment. These included proteins that were related to metabolism, antioxidants, structural proteins, protein degradation and signal transduction. Of particular interest was the regulation of a number of proteins involved in stress response--peroxiredoxin-2, peroxiredoxin-3 and peroxiredoxin-6-all of which were shown to be down-regulated with H₂O₂ exposure. The effect was reversed following TRF treatment. The expression of peroxiredoxin-2 and peroxiredoxin-6 was confirmed by quantitative reverse transcriptase polymerase chain reaction. These results suggested that TRF directly influenced the expression dynamics of the peroxiredoxin-2, thus improving the cells ability to resist damage caused by oxidative stress.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
  13. Optimization of protein extraction for proteomic analyses of fresh and frozen "Musang King" durian pulps
    Tan XY, Misran A, Daim LDJ, Lau BYC
    Food Chem, 2021 May 01;343:128471.
    PMID: 33143964 DOI: 10.1016/j.foodchem.2020.128471
    Four different methods were evaluated to extract proteins from "Musang King" durian pulps and subsequently proteins with different abundance between fresh and long term frozen storage were identified using two-dimensional polyacrylamide gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometer analyses. The acetone-phenol method was found to produce good protein yields and gave the highest gel resolution and reproducibility. Differential protein analyses of the durian pulp revealed that 15 proteins were down-regulated and three other proteins were up-regulated after a year of frozen storage. Isoflavone reductase-like protein, S-adenosyl methionine synthase, and cysteine synthase isoform were up-regulated during frozen storage. The down-regulation of proteins in frozen durian pulps indicated that frozen storage has affected proteins in many ways, especially in their functions related to carbohydrate and energy metabolisms, cellular components, and transport processes. This study will enable future detailed investigations of proteins associated with quality attributes of durians to be studied.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  14. Annexin A2 and alpha actinin 4 expression correlates with metastatic potential of primary endometrial cancer
    Mittal P, Klingler-Hoffmann M, Arentz G, Winderbaum L, Kaur G, Anderson L, et al.
    Biochim Biophys Acta Proteins Proteom, 2017 Jul;1865(7):846-857.
    PMID: 27784647 DOI: 10.1016/j.bbapap.2016.10.010
    The prediction of lymph node metastasis using clinic-pathological data and molecular information from endometrial cancers lacks accuracy and is therefore currently not routinely used in patient management. Consequently, although only a small percentage of patients with endometrial cancers suffer from metastasis, the majority undergo radical surgery including removal of pelvic lymph nodes. Upon analysis of publically available data and published research, we compiled a list of 60 proteins having the potential to display differential abundance between primary endometrial cancers with versus those without lymph node metastasis. Using data dependent acquisition LC-ESI-MS/MS we were able to detect 23 of these proteins in endometrial cancers, and using data independent LC-ESI-MS/MS the differential abundance of five of those proteins was observed. The localization of the differentially expressed proteins, was visualized using peptide MALDI MSI in whole tissue sections as well as tissue microarrays of 43 patients. The proteins identified were further validated by immunohistochemistry. Our data indicate that annexin A2 protein level is upregulated, whereas annexin A1 and α actinin 4 expression are downregulated in tumours with lymph node metastasis compared to those without lymphatic spread. Moreover, our analysis confirmed the potential of these markers, to be included in a statistical model for prediction of lymph node metastasis. The predictive model using highly ranked m/z values identified by MALDI MSI showed significantly higher predictive accuracy than the model using immunohistochemistry data. In summary, using publicly available data and complementary proteomics approaches, we were able to improve the prediction model for lymph node metastasis in EC.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
  15. Fulltext Purification and Characterization of a Novel NAD(P)+-Farnesol Dehydrogenase from Polygonum minus Leaves
    Ahmad-Sohdi NA, Seman-Kamarulzaman AF, Mohamed-Hussein ZA, Hassan M
    PLoS One, 2015;10(11):e0143310.
    PMID: 26600471 DOI: 10.1371/journal.pone.0143310
    Juvenile hormones have attracted attention as safe and selective targets for the design and development of environmentally friendly and biorational insecticides. In the juvenile hormone III biosynthetic pathway, the enzyme farnesol dehydrogenase catalyzes the oxidation of farnesol to farnesal. In this study, farnesol dehydrogenase was extracted from Polygonum minus leaves and purified 204-fold to apparent homogeneity by ion-exchange chromatography using DEAE-Toyopearl, SP-Toyopearl, and Super-Q Toyopearl, followed by three successive purifications by gel filtration chromatography on a TSK-gel GS3000SW. The enzyme is a heterodimer comprised of subunits with molecular masses of 65 kDa and 70 kDa. The optimum temperature and pH were 35°C and pH 9.5, respectively. Activity was inhibited by sulfhydryl reagents, metal-chelating agents and heavy metal ions. The enzyme utilized both NAD+ and NADP+ as coenzymes with Km values of 0.74 mM and 40 mM, respectively. Trans, trans-farnesol was the preferred substrate for the P. minus farnesol dehydrogenase. Geometrical isomers of trans, trans-farnesol, cis, trans-farnesol and cis, cis-farnesol were also oxidized by the enzyme with lower activity. The Km values for trans, trans-farnesol, cis, trans-farnesol and cis, cis-farnesol appeared to be 0.17 mM, 0.33 mM and 0.42 mM, respectively. The amino acid sequences of 4 tryptic peptides of the enzyme were analyzed by MALDI-TOF/TOF-MS spectrometry, and showed no significant similarity to those of previously reported farnesol dehydrogenases. These results suggest that the purified enzyme is a novel NAD(P)+-dependent farnesol dehydrogenase. The purification and characterization established in the current study will serve as a basis to provide new information for recombinant production of the enzyme. Therefore, recombinant farnesol dehydrogenase may provide a useful molecular tool in manipulating juvenile hormone biosynthesis to generate transgenic plants for pest control.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  16. Fulltext Cadmium toxicity induced alterations in the root proteome of green gram in contrasting response towards iron supplement
    Muneer S, Hakeem KR, Mohamed R, Lee JH
    Int J Mol Sci, 2014;15(4):6343-55.
    PMID: 24739807 DOI: 10.3390/ijms15046343
    Cadmium signifies a severe threat to crop productivity and green gram is a notably iron sensitive plant which shows considerable variation towards cadmium stress. A gel-based proteomics analysis was performed with the roots of green gram exposed to iron and cadmium combined treatments. The resulting data show that twenty three proteins were down-regulated in iron-deprived roots either in the absence (-Fe/-Cd) or presence (-Fe/+Cd) of cadmium. These down-regulated proteins were however well expressed in roots under iron sufficient conditions, even in the presence of cadmium (+Fe/+Cd). The functional classification of these proteins determined that 21% of the proteins are associated with nutrient metabolism. The other proteins in higher quantities are involved in either transcription or translation regulation, and the rest are involved in biosynthesis metabolism, antioxidant pathways, molecular chaperones and stress response. On the other hand, several protein spots were also absent in roots in response to iron deprivation either in absence (-Fe/-Cd) or presence (-Fe/+Cd) of cadmium but were well expressed in the presence of iron (+Fe/+Cd). Results suggest that green gram plants exposed to cadmium stress are able to change the nutrient metabolic balance in roots, but in the mean time regulate cadmium toxicity through iron supplements.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  17. Fulltext Quorum sensing activity in Pandoraea pnomenusa RB38
    Ee R, Lim YL, Kin LX, Yin WF, Chan KG
    Sensors (Basel), 2014;14(6):10177-86.
    PMID: 24919016 DOI: 10.3390/s140610177
    Strain RB38 was recovered from a former dumping area in Malaysia. MALDI-TOF mass spectrometry and genomic analysis identified strain RB-38 as Pandoraea pnomenusa. Various biosensors confirmed its quorum sensing properties. High resolution triple quadrupole liquid chromatography-mass spectrometry analysis was subsequently used to characterize the N-acyl homoserine lactone production profile of P. pnomenusa strain RB38, which validated that this isolate produced N-octanoyl homoserine lactone as a quorum sensing molecule. This is the first report of the production of N-octanoyl homoserine lactone by P. pnomenusa strain RB38.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  18. Fulltext Quorum sensing activity of Aeromonas caviae strain YL12, a bacterium isolated from compost
    Lim YL, Ee R, Yin WF, Chan KG
    Sensors (Basel), 2014 Apr 22;14(4):7026-40.
    PMID: 24759107 DOI: 10.3390/s140407026
    Quorum sensing is a well-studied cell-to-cell communication method that involves a cell-density dependent regulation of genes expression mediated by signalling molecules. In this study, a bacterium isolated from a plant material compost pile was found to possess quorum sensing activity based on bioassay screening. Isolate YL12 was identified using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and molecular typing using rpoD gene which identified the isolate as Aeromonas caviae. High resolution tandem mass spectrometry was subsequently employed to identify the N-acyl homoserine lactone profile of Aeromonas caviae YL12 and confirmed that this isolate produced two short chain N-acyl homoserine lactones, namely C4-HSL and C6, and the production was observed to be cell density-dependent. Using the thin layer chromatography (TLC) bioassay, both AHLs were found to activate C. violaceum CV026, whereas only C6-HSL was revealed to induce bioluminescence expression of E. coli [pSB401]. The data presented in this study will be the leading steps in understanding the role of quorum sensing in Aeromonas caviae strain YL12.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  19. Fulltext Characterization of affinity-purified isoforms of Acinetobacter calcoaceticus Y1 glutathione transferases
    Chee CS, Tan IK, Alias Z
    ScientificWorldJournal, 2014;2014:750317.
    PMID: 24892084 DOI: 10.1155/2014/750317
    Glutathione transferases (GST) were purified from locally isolated bacteria, Acinetobacter calcoaceticus Y1, by glutathione-affinity chromatography and anion exchange, and their substrate specificities were investigated. SDS-polyacrylamide gel electrophoresis revealed that the purified GST resolved into a single band with a molecular weight (MW) of 23 kDa. 2-dimensional (2-D) gel electrophoresis showed the presence of two isoforms, GST1 (pI 4.5) and GST2 (pI 6.2) with identical MW. GST1 was reactive towards ethacrynic acid, hydrogen peroxide, 1-chloro-2,4-dinitrobenzene, and trans,trans-hepta-2,4-dienal while GST2 was active towards all substrates except hydrogen peroxide. This demonstrated that GST1 possessed peroxidase activity which was absent in GST2. This study also showed that only GST2 was able to conjugate GSH to isoproturon, a herbicide. GST1 and GST2 were suggested to be similar to F0KLY9 (putative glutathione S-transferase) and F0KKB0 (glutathione S-transferase III) of Acinetobacter calcoaceticus strain PHEA-2, respectively.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  20. 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: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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