Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.16.3.1 (ceruloplasmin)
 5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The whitefly Bemisia tabaci is an important pest of worldwide agriculture. Previous work has shown that B. tabaci actively suppresses host plant defenses, but our knowledge of the specific mechanisms involved remains limited. Here we describe a B. tabaci salivary protein, the ferritin BtFer1, and its role in facilitating exploitation of host plants. We show that BtFer1 exhibits Fe2+ binding ability and ferroxidase activity, and that secretion of BtFer1 during B. tabaci feeding suppresses H2O2-generated oxidative signals in tomato (Solanum lycopersicum). Silencing BtFer1 enhanced the induction of the jasmonic acid (JA)-mediated defense signaling pathway in response to whitefly feeding, and led to increased callose deposition and the production of proteinase inhibitors that prevent whiteflies from continuously ingesting and digesting phloem sap. Consistent with these effects, silencing BtFer1 reduced whitefly survival on tomato but not on artificial diet. Using a JA-deficient spr2 mutant plant further showed that suppression of JA defenses by BtFer1 is sufficient to increase B. tabaci survival. Taken together, these results demonstrate that BtFer1 acts as an effector protein that mediates whitefly-tomato interactions. These findings represent an important step forward in understanding the molecular mechanisms by which whiteflies and other insect herbivores suppress host plant defenses.
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PMID:A salivary ferritin in the whitefly suppresses plant defenses and facilitates host exploitation. 3094 71

Neutrophil myeloperoxidase (MPO) plays an important role in protecting the body against infections. MPO products - hypohalous acids and phenoxyl radicals - are strong oxidants that can damage not only foreign intruders but also host tissues, including blood plasma proteins. Here, we compared the MPO-induced oxidation of two plasma proteins with antioxidant properties - human serum albumin (HSA) and ceruloplasmin (CP). Incubation of both proteins with hypochlorite (NaOCl) or catalytically active MPO (MPO + H2O2), which synthesizes hypochlorous acid (HOCl) in the presence of chloride ions, resulted in the quenching of protein tryptophan fluorescence. Oxidation-induced changes in the structures of HSA and CP were different. HSA efficiently neutralized MPO-generated oxidants without protein aggregation, while CP oxidation resulted in the formation of large aggregates stabilized by strong covalent bonds between the aromatic amino acid residues. Tyrosine is present in the plasma as free amino acid and also as a component of the polypeptide chains of the proteins. The number of tyrosine residues in a protein does not determine its propensity for aggregate formation. In the case of CP, protein aggregation was primarily due to the high content of tryptophan residues in its polypeptide chain. MPO-dependent oxidation of free tyrosine results in the formation of tyrosyl radicals, that do not oxidize aromatic amino acid residues in proteins because of the high rate of recombination with dityrosine formation. At the same time, free tyrosine can influence MPO-induced protein oxidation due to its ability to modulate HOCl synthesis in the MPO active site.
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PMID:Myeloperoxidase-Induced Oxidation of Albumin and Ceruloplasmin: Role of Tyrosines. 3123 65

Dps proteins (DNA-binding proteins from starved cells) have been found to detoxify H2O2. At their catalytic centers, the ferroxidase center (FOC), Dps proteins utilize Fe2+ to reduce H2O2 and therefore play an essential role in the protection against oxidative stress and maintaining iron homeostasis. Whereas most bacteria accommodate one or two Dps, there are five different Dps proteins in Nostoc punctiforme, a phototrophic and filamentous cyanobacterium. This uncommonly high number of Dps proteins implies a sophisticated machinery for maintaining complex iron homeostasis and for protection against oxidative stress. Functional analyses and structural information on cyanobacterial Dps proteins are rare, but essential for understanding the function of each of the NpDps proteins. In this study, we present the crystal structure of NpDps4 in its metal-free, iron- and zinc-bound forms. The FOC coordinates either two iron atoms or one zinc atom. Spectroscopic analyses revealed that NpDps4 could oxidize Fe2+ utilizing O2, but no evidence for its use of the oxidant H2O2 could be found. We identified Zn2+ to be an effective inhibitor of the O2-mediated Fe2+ oxidation in NpDps4. NpDps4 exhibits a FOC that is very different from canonical Dps, but structurally similar to the atypical one from DpsA of Thermosynechococcus elongatus. Sequence comparisons among Dps protein homologs to NpDps4 within the cyanobacterial phylum led us to classify a novel FOC class: the His-type FOC. The features of this special FOC have not been identified in Dps proteins from other bacterial phyla and it might be unique to cyanobacterial Dps proteins.
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PMID:The Dps4 from Nostoc punctiforme ATCC 29133 is a member of His-type FOC containing Dps protein class that can be broadly found among cyanobacteria. 3136 77


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