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Last updated: 13th August 2010

Literature
Alterations of the salivary secretory peptidome profile in children affected by type 1 diabetes.
Cabras T, Pisano E, Mastinu A, Denotti G, Pusceddu PP, Inzitari R, Fanali C, Nemolato S, Castagnola M, Messana I
Cagliari University, Italy;
Molecular & cellular proteomics : MCP 2010 Jun
Abstract
The acidic soluble fraction of whole saliva of type 1 diabetic children was analyzed by RP-HPLC-ESI-MS and compared to that one of sex- and age-matched control subjects. Salivary acidic proline-rich phosphoproteins, histatins, alpha-defensins, salivary cystatins, statherin, proline-rich peptide P-B, beta-thymosins, S100A8 and S100A9*, as well some naturally occurring peptides derived from salivary acidic proline-rich phosphoproteins, histatins, statherin, and P-B peptide, were detected and quantified on the basis of the extracted ion current peak area. The level of phosphorylation of salivary acidic proline-rich phosphoproteins, histatin 1, statherin and S100A9* and the percentage of truncated forms of salivary acidic proline-rich phosphoproteins was also determined in the two groups. The study revealed that statherin, proline-rich peptide P-B, P-C peptide, and histatins, were significantly less concentrated in saliva of diabetic subjects than in controls, while concentration of alpha-defensins 1, 2 and 4 and S100A9* was higher. The low concentration of P-C peptide was paralleled by high levels of some of its fragments. On the whole, the study highlighted the severe impairment of the repertoire of peptides involved in the safeguard of the oral cavity in children with diabetes, as well as an higher concentration of the proinflammatory mediator S100A9* with respect to normal children.
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A new allergen from ragweed (Ambrosia artemisiifolia) with homology to Art v 1 from mugwort.
Leonard R, Wopfner N, Pabst M, Stadlmann J, Petersen BO, Duus JO, Himly M, Radauer C, Gadermaier G, Ra´a´i-Fazeli E, Ferreira F, Altmann F
Department of Chemistry, University of Natural Resources and Applied Life Sciences BOKU, 1190 Vienna, Austria.
J Biol Chem. 2010 Aug 27;285(35):27192-200.
Abstract
Art v 1, the major pollen allergen of the composite plant mugwort (Artemisia vulgaris) has recently been identified as a thionin-like protein with a bulky arabinogalactan-protein moiety. A close relative of mugwort, ragweed (Ambrosia artemisiifolia) is an important allergen source in North America and since 1990 ragweed becomes a growing health concern also in Europe. Weed pollen sensitized patients demonstrated IgE reactivity to a ragweed pollen protein of apparently 29- 31 kDa. This reaction could be inhibited by the mugwort allergen Art v 1. The purified ragweed pollen protein consisted of a 57 amino acid long defensin-like domain with high homology to Art v 1 and a C-terminal proline-rich domain. This part contained hydroxyproline-linked arabinogalactan chains with one galactose and 5 to 20 and more alpha-arabinofuranosyl residues with some beta-arabinoses in terminal positions as revealed by high field NMR. The ragweed protein contained only small amounts of the single hydroxyproline-linked beta-arabinosyl residues, which form an important IgE binding determinant in Art v 1. cDNA clones for this protein were obtained from ragweed flowers. Immunological characterization revealed that the recombinant ragweed protein reacted with more than 30% of the weed pollen allergic patients. Therefore this protein from ragweed pollen constitutes a novel important ragweed allergen and has been designated Amb a 4.
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Interleukin-17A is required to suppress invasion of Salmonella enterica serovar Typhimurium to enteric mucosa.
Mayuzumi H, Inagaki-Ohara K, Uyttenhove C, Okamoto Y, Matsuzaki G
Molecular Microbiology Group, Center of Molecular Biosciences, Tropical Biosphere Research Centre, University of the Ryukyus, Senbaru, Nishihara, Okinawa.
Immunology 2010 Jun
Abstract
Summary Salmonella enterica serovar Typhimurium (S. typhimurium) causes a localized enteric infection and its elimination is dependent on a T helper type 1 immune response. However, the mechanism of the protective immune response against the pathogen in gut-associated lymphoid tissue (GALT) at an early stage of the infection is not yet clarified. Here, we show that interleukin-17A (IL-17A) was constitutively expressed in GALT; it was also detected on crypt and epithelial cells of the small intestine. Neutralization of the IL-17A in the intestinal lumen exacerbated epithelial damage induced by intestinal S. typhimurium infection at an early stage of the infection. The result suggests that IL-17A has a pivotal role in the immediate early stage of protection against bacterial infection at the intestinal mucosa. As IL-17A neutralization also suppressed the constitutive localization of beta-defensin 3 (BD3), an IL-17A-induced antimicrobial peptide, at the apical site of the intestinal mucosa, it is estimated that IL-17A constitutively induces the expression of the antimicrobial peptide to kill invading pathogens at the epithelial surface immediately after the infection. In contrast, interferon-gamma is induced around 3 days after S. typhimurium infection, and its expression level increases thereafter. Taken together, the findings lead to the hypothesis that IL-17A participates in the immediate early stage of protection against S. typhimurium intestinal infection whereas interferon-gamma is important at a later stage of the infection.
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Expression of human beta-defensin-2 in the prostate.
Kim HJ, Jung JR, Kim HJ, Lee SY, Chang IH, Lee TJ, Kim W, Myung SC
Advanced Urogenital Disease Research Center, Chung-Ang University College of Medicine, Seoul, Korea.
BJU international 2010 Jun
Abstract
OBJECTIVE To investigate the expression and regulation of human beta-defensin-2 (HBD-2) in the prostate. MATERIALS AND METHODS Normal human prostate epithelial cell line (RWPE-1), human prostate cancer cell lines (DU-145, PC-3), and paraffin-embedded prostate tissue from patients with benign prostatic hyperplasia (BPH) were analysed by RT-PCR and immunohistochemical staining. HBD-2 expression was also analysed by RT-PCR and ELISA in RWPE-1 cells treated with lipopolysaccharide (LPS). Nuclear factor-kappaB (NF-kappaB) activation was assessed by IkappaBalpha immunoblotting and electrophoretic mobility shift assay (EMSA). RESULTS BPH tissue and all of the tested prostate cell lines other than PC-3 constitutively express HBD-2 mRNA. HBD-2 protein was strongly detected in prostate gland tissue surrounded by inflammatory cells including macrophages. Exposure to LPS induced HBD-2 upregulation and NF-kappaB activation, as assessed by IkappaBalpha phosphorylation and degradation in RWPE-1 cells. Bay11-7082, an NF-kappaB inhibitor prevented LPS-induced HBD-2 production in RWPE-1 cells. CONCLUSIONS Prostate epithelial cells may constitutively express HBD-2, and its expression was upregulated by LPS. Our data indicate that HBD-2 may be an important immunomodulatory factor in prostate function. Expression of HBD-2 in normal prostates and the potential role of HBD-2 in prostatitis and BPH should be addressed in the future.
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Elevated plasma levels of antimicrobial polypeptides in patients with severe sepsis.
Berkestedt I, Herwald H, Ljunggren L, Nelson A, Bodelsson M
Department of Anaesthesiology and Intensive Care, Lund University, and Lund University Hospital, Lund, Sweden.
J Innate Immun. 2010;2(5):478-82.
Abstract
We wanted to investigate if plasma levels of antimicrobial polypeptides (AMPs) are increased in severe sepsis and if they correlate with severity and mortality. Samples were collected from 31 sepsis patients at the intensive care unit. The Sequential Organ Failure Assessment (SOFA) score and 90-day mortality were registered, and inflammatory markers and AMP levels were measured by ELISA. A median SOFA score (13) and cardiovascular SOFA score (3) indicated multiorgan failure with severe circulatory derangement, and elevated cytokine levels indicated inflammatory activation. Levels of bactericidal/permeability-increasing protein, heparin-binding protein, alpha-defensins and lactoferrin but not LL-37 were elevated in sepsis patients compared with controls. Bactericidal/permeability-increasing protein levels correlated with mortality, with lower levels in survivors. Levels of all AMPs, except LL-37, positively correlated with the cardiovascular SOFA score. In conclusion, levels of several AMPs are increased in sepsis and correlate with circulatory derangement. This probably reflects neutrophil activation as part of an innate immune response.
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Mammalian peptide isomerase: platypus-type activity is present in mouse heart.
Koh JM, Chow SJ, Crossett B, Kuchel PW
School of Molecular Biosciences, Building G08, University of Sydney, NSW 2006, Australia.
Chem. Biodivers. 2010 Jun;7 (6):1603-11
Abstract
Male platypus (Ornithorhynchus anatinus) venom has a peptidyl aminoacyl L/D-isomerase (hereafter called peptide isomerase) that converts the second amino acid residue in from the N-terminus from the L- to the D-form, and vice versa. A reversed-phase high-performance liquid chromatography (RP-HPLC) assay has been developed to monitor the interconversion using synthetic hexapeptides derived from defensin-like peptide-2 (DLP-2) and DLP-4 as substrates. It was hypothesised that animals other than the platypus would have peptide isomerase with the same substrate specificity. Accordingly, eight mouse tissues were tested and heart was shown to have the activity. This is notable for being the first evidence of a peptide isomerase being present in a higher mammal and heralds finding the activity in man.
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Analysis and classification of circular proteins in CyBase.
Kaas Q, Craik DJ
The University of Queensland, Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, Brisbane, 4072 QLD Australia.
Biopolymers 2010 May
Abstract
CyBase is a database dedicated to the study of the sequences and three-dimensional structures of ribosomally synthesized, backbone cyclized proteins and their synthetic variants. This article describes CyBase data and tools that are useful in the analysis of circular proteins. Circular proteins have now been discovered in organisms from all kingdoms of life, and given the current rate of discovery they could soon number in the thousands. Presently CyBase manages 427 protein sequences, 106 nucleic acid sequences, and 49 protein three-dimensional structures from 44 different species. Circular proteins are grouped into distinct classes according to their origin and sequence similarities. These classes include trypsin inhibitors, bacterial proteins, mushroom toxins, cyclotides and cyclic defensins from primates. Several protein classification types are used in CyBase to designate proteins extracted from natural resources (wild type and precursor) or engineered (modified wild type, grafted, mutant, cyclic permutant, and acyclic permutant). CyBase has tools for the analysis of mass spectrum fingerprints of cyclic peptides, and assists in the discovery of new circular proteins. Some of the developments detailed here have been made specifically for the largest class of circular proteins, the cyclotides, but could be adapted for other classes of cyclic proteins. The cyclotide-specific tools include two-dimensional representations of domains and alternative displays of alignments for precursor sequences. This alignment prompted us to propose a revision of the cyclotide precursor organization, in which the repeated regions now include a small C-terminal region, which appears to have a significant role in the biosynthesis of mature cyclotides. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2010.
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Circular proteins and mechanisms of cyclization.
Conlan BF, Gillon AD, Craik DJ, Anderson MA
Department of Biochemistry, La Trobe University, Melbourne, Victoria 3086, Australia.
Biopolymers 2010 May
Abstract
Cyclization via head-to-tail linkage of the termini of a peptide chain occurs in only a small percentage of proteins but engenders the resultant cyclic proteins with exceptional stability. The mechanisms involved are poorly understood and this review attempts to summarize what is known of the events that lead to cyclization. Cyclic proteins are found in both prokaryotic and eukaryotic species. The prokaryotic circular proteins include the bacteriocins and pilins. The eukaryotic circular proteins in mammals include the theta defensins, found in rhesus macaques, and the retrocyclins. Two types of cyclic proteins have been found in plants, the sunflower trypsin inhibitor and the larger, more prolific, group known as cyclotides. The cyclotides from Oldenlandia affinis, the plant in which these cyclotides were first discovered, are processed by an asparaginyl endopeptidase which is a cysteine protease. Cysteine proteases are commonly associated with transpeptidation reactions, which, for suitable substrates can lead to cyclization events. These proteases cleave an amide bond and form an acyl enzyme intermediate before nucleophilic attack of the amine group of the N-terminal residue to form a peptide bond, resulting in a cyclic peptide. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2010.
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Cyclotides are a component of the innate defence of Oldenlandia affinis.
Mylne JS, Wang CK, van der Weerden NL, Craik DJ
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
Biopolymers 2010 May
Abstract
Cyclotides are small cysteine-rich plant peptides similar in size and processing to the defensins. Long-term growth of the Rubiaceae family plant Oldenlandia affinis under different conditions reveals a diverse cyclotide gene and peptide expression profile, including tissue specificity, suggesting that different cyclotides are regulated differently both spatially and in response to the environment. To determine whether cyclotide precursor gene regulation was dynamic we exposed O. affinis to a range of abiotic, biotic and hormonal stimuli and monitored Oak1-4 expression over a 48 hour period. Unlike some defensins, the genes for cyclotide precursor proteins Oak1-4 did not display dynamic change, indicating that they contribute to the basal defence of O. affinis. Despite this lack of dynamism, the cyclotide profile of plants grown on plates differed markedly from field-grown plants and so prompted attempts to discover novel cyclotides and precursor genes. The two most abundant cyclotides from plate-grown O. affinis were sequenced and one was found to be an unusual linear cyclotide derivative, kalata B20-lin. Degenerate PCR of plate-grown O. affinis obtained five novel cyclotide genes including Oak9 which encodes for kalata B20-lin and appears to have arisen by the presence of a premature stop codon. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2010.
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Arabidopsis thaliana plant defensin AtPDF1.1 is involved in the plant response to biotic stress.
De Coninck BM, Sels J, Venmans E, Thys W, Goderis IJ, Carron D, Delaur SL, Cammue BP, De Bolle MF, Mathys J
Center of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
New Phytol. 2010 Sep;187(4):1075-88.
Abstract
*Previously, it was shown that the Arabidopsis thaliana plant defensins AtPDF1.1 (At1g75830) and AtPDF1.2a (At5g44420) exert in vitro antimicrobial properties and that their corresponding genes are expressed in seeds and induced in leaves upon pathogen attack, respectively. *In this study, the expression profile of both AtPDF1.1 and AtPDF1.2a is analysed in wild-type plants upon different stress-related treatments and the effect of modulation of their expression in transgenic plants is examined in both host and nonhost resistance. *AtPDF1.1, which was originally considered to be seed-specific, is demonstrated to be locally induced in leaves upon fungal attack and exhibits an expression profile distinct from that of AtPDF1.2a, a gene frequently used as marker for the ethylene/jasmonate-mediated signaling pathway. Transgenic plants with modulated AtPDF1.1 or AtPDF1.2a gene expression show no altered phenotype upon Botrytis cinerea inoculation. However, constitutive overexpression of AtPDF1.1 in A. thaliana leads to a reduction in symptoms caused by the nonhost Cercospora beticola causing non-spreading spots on A. thaliana leaves. *These results indicate that AtPDF1.1 and AtPDF1.2a clearly differ regarding their expression profile and functionality in planta. It emphasizes the additional level of complexity and fine-tuning within the highly redundant plant defensin genes in A. thaliana.
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