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Ferritin is a conserved iron binding protein existing ubiquitously in prokaryotes and eukaryotes. In this study, the gene encoding a ferritin M subunit homologue (SoFer1) was cloned from red drum (Sciaenops ocellatus) and analyzed at expression and functional levels. The open reading frame of SoFer1 is 531 bp and preceded by a 5′-untranslated region that contains a putative Iron Regulatory Element (IRE) preserved in many ferritins. The deduced amino acid sequence of SoFer1 possesses both the ferroxidase center of mammalian H ferritin and the iron nucleation site of mammalian L ferritin. Expression of SoFer1 was tissue specific and responded positively to experimental challenges with Gram-positive and Gram-negative fish pathogens. Treatment of red drum liver cells with iron, copper, and oxidant significantly upregulated the expression of SoFer1 in time-dependent manners. To further examine the potential role of SoFer1 in antioxidation, red drum liver cells transfected transiently with SoFer1 were prepared. Compared to control cells, SoFer1 transfectants exhibited reduced production of reactive oxygen species following H2O2 challenge. Finally, to examine the iron binding potential of SoFer1, SoFer1 was expressed in and purified from Escherichia coli as a recombinant protein. Iron-chelating analysis showed that purified recombinant SoFer1 was capable of iron binding. Taken together, these results suggest that SoFer1 is likely to be a functional ferritin involved in iron sequestration, host immune defence against bacterial infection, and antioxidation.  相似文献   

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Ferritin is a major eukaryotic protein and in humans is the protein of iron storage. A partial gene fragment of ferritin (255 bp) taken from the total RNA of Periserrula leucophryna, was amplified by RT-PCR using oligonucleotide primers designed from the conserved metal binding domain of eukaryotic ferritin and confirmed by DNA sequencing. Using the 32P-labeled partial ferritin cDNA fragment, 28 different clones were obtained by the screening of the P. leucophryna cDNA library prepared in the Uni-ZAP XR vector, sequenced and characterized. The longest clone was named the PLF (Periserrula leucophryna ferritin) gene and the nucleotide and amino acid sequences of this novel gene were deposited in the GenBank databases with accession numbers DQ207752 and ABA55730, respectively. The entire cDNA of PLF clone was 1109 bp (CDS: 129-653), including a coding nucleotide sequence of 525 bp, a 5'-untranslated region of 128 bp, and a 3'-noncoding region of 456 bp. The 5'-UTR contains a putative iron responsive element (IRE) sequence. Ferritin has an open reading frame encoding a polypeptide of 174 amino acids including a hydrophobic signal peptide of 17 amino acids. The predicted molecular weights of the immature and mature ferritin were calculated to be 20.3 kDa and 18.2 kDa, respectively. The region encoding the mature ferritin was subcloned into the pT7-7 expression vector after PCR amplification using the designed primers and included the initiation and termination codons; the recombinant clones were expressed in E. coli BL21(DE3) or E. coli BL21(DE3)pLysE. SDS-PAGE and western blot analysis showed that a ferritin of approximately 18 kDa (mature form) was produced and that by iron staining in native PAGE, it is likely that the recombinant ferritin is correctly folded and assembled into a homopolymer composed of a single subunit.  相似文献   

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利用cDNA末端快速扩增(RACE)技术克隆了鳜(Siniperca chuatsi)脑中2种生长抑素受体(somatostatin receptor,SSTR2和SSTR3)cDNA全长序列。结果显示,鳜SSTR2 cDNA全长1 820 bp,含开放阅读框1 146 bp,编码382个氨基酸;SSTR3 cDNA全长1 874 bp,含开放阅读框1 458 bp,编码486个氨基酸。SSTR均由5个结构区域组成:N端、7个转膜区(TMD)、3个细胞外袢(ECLs)、4个细胞内袢(ICLs)和C末端。NJ系统进化树分析显示,鳜SSTR2和SSTR3分别形成相对独立的分支,两者间的氨基酸序列相似度为51.2%,表明它们是由不同基因编码而成。利用实时荧光定量RT-PCR技术检测了鳜SSTR2和SSTR3 mRNA的组织表达特征,它们均在多种组织中广泛表达,SSTR2 mRNA在肝中表达量最高,SSTR3 mRNA在胃中表达量最高。SSTR2、SSTR3表达差异反映它们可能参与不同生理调控作用。  相似文献   

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The ability of the microbial Siderophores deferriferrichrome, deferriferrichrome A, and enterobactin to remove iron from ferritin has been investigated. In contrast to previously published data with other chelators, all three Siderophores rapidly released iron from the mammalian storage protein Enterobactin was found most efficient at removing ferritin-bound iron. Using this siderophore, the mechanism by which ferritin sequesters iron was studied The relative iron saturation level of ferritin influenced the rate of chelation by the microbial Siderophores.  相似文献   

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Ferritin is an evolutionarily conserved protein that plays an important role in iron storage and detoxification. In this study, the gene encoding a ferritin H subunit homologue (SmFer1) was cloned from turbot (Scophthalmus maximus) and analyzed at the expression and functional levels. The open reading frame of SmFer1 is 534 bp and preceded by a 5′-untranslated region that contains a putative Iron Regulatory Element (IRE). The deduced amino acid sequence of SmFer1 shares extensive sequence identities with the H ferritins of a number of fish species and contains the ferroxidase center that is preserved in ferritin H subunits. Examination of tissue specific expression indicated that SmFer1 expression was most abundant in muscle, liver, and blood. Experimental infection with bacterial pathogens induced significant induction of SmFer1; however, the magnitudes of induction effected by Gram-negative pathogens were much higher than that induced by Gram-positive pathogen. Consistently, lipopolysaccharide (LPS) challenge drastically augmented SmFer1 expression. In addition to bacterial pathogens and LPS, poly(I:C) also induced a strong but transient induction of SmFer1 which differs in profile from those induced by bacterial pathogens. In vitro iron-chelating analysis showed that recombinant SmFer1 purified from Escherichia coli was able to bind ferrous iron in a concentration-dependent manner. To examine whether SmFer1, with its iron-chelating capacity, could have any effect on the infection of bacterial pathogens, purified recombinant SmFer1 was subjected to bacteriostatic analysis and proved to be able to inhibit the growth of the fish pathogen Listonella anguillarum which enhanced SmFer1 expression upon infection. Taken together, these results suggest that SmFer1 is likely to play a role in both iron storage and immune defense against microbial infections.  相似文献   

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Ferritin is a storage protein that plays a key role in iron metabolism. In this study, we report on the sequence characterization of a ferritin-coding cDNA in Eisenia andrei earthworms isolated by RT-PCR using degenerated primers, and we suggest the presence of a putative IRE in the 5′-UTR of ferritin mRNA. The obtained ferritin sequence was compared with those of other animals showing sequence and structure homology in consensus sites, including the iron-responsive element (IRE) and ferroxidase centers. Despite the sequence homology in the E. andrei mRNA of ferritin with the sequences of other animals in consensus IRE sites, the presented cytosine in the IRE of E. andrei ferritin in the expected position does not form a conventional bulge. The presence of ferritin in the coelomic fluid of E. andrei was proven by iron staining assay. Moreover, aconitase activity in the coelomic fluid was assessed by aconitase assay, suggesting the presence of an iron regulatory protein. Quantitative analysis revealed changes in the gene expression levels of ferritin in coelomocytes in response to bacterial challenge, reaching the maximum level 8 h after the stimulation with both Gram-positive and Gram-negative bacteria.  相似文献   

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Hemp (Cannabis sativa L.) seeds have been recognized as a nutritional protein source for humans and animals. In this study, gene families encoding precursor polypeptides of three storage protein classes, including six 11S edestin, two 2S albumin and one 7S vicilin-like genes were identified and characterized from an inbred line of hemp. All edestins showed typical 11S globulin features but based on the amino acid composition, they were grouped in three edestin types (type1, -2 and -3). Genes encoding edestin type1 and -3 were very close to each other in a DNA fragment of 16 071 bp, whereas the two isoforms of edestin type2 were linked on a different DNA fragment of 8 232 bp and arranged in a tailto- tail fashion. All edestin types were very rich in arginine and glutamic acid, but edestin type3 was the richest in cysteine and methionine. Regarding the 2S albumin (Cs2S) two genes were identified in a fragment of 13 738 bp in a tail-to-head array. Finally, only one 7S-vicilin like gene (Cs7S) that exhibited typical 7S vicilin features, such as the presence of two cupin domains and several N-glycosylation sites, was isolated. Southern blot hybridization is in agreement with the number of genes isolated, and real-time qPCR analysis revealed that all genes are expressed in the seed. The highest expression was observed for edestin type1 (CsEde1) and Cs2S, whereas the lowest expression was detected for Cs7S. The results of this study provide a complete overview of the genes encoding hemp storage proteins and significantly advance our knowledge on the organization of these gene families.  相似文献   

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《Insect Biochemistry》1989,19(6):587-602
In mammals, the iron storage protein ferritin is predominantly synthesized on free polysomes and accumulates in the cytosol but some is secreted and circulates in the blood as serum ferritin. In insect tissues, on the other hand, iron-containing holoferritin accumulates in the vacuolar system and can be secreted through the Golgi complex. The midgut can secrete it to the gut lumen and other tissues to the hemolymph.Ferritin was isolated from the midgut and hemolymph of fifth instar larvae of Calpodes ethlius, Lepidoptera, Hesperiidae. This holoferritin is stable to heat (75°C) or in the presence of SDS, proteinase K, or urea, has an Mr above 600,000, contains iron and resembles mammalian ferritins in appearance by electron microscopy. Calpodes ferritin is a glycoprotein having N-linked high-mannose oligosaccharides. It is not antigenically related to horse ferritin but is related to that from Manduca sexta, Lepidoptera, Sphingidae. In its native form, Calpodes ferritin has only 3 isoforms with a pI 6.5–7 suggesting a more uniform subunit composition than that in vertebrates. It has two principle subunits, with relative Mrs of 24,000 (L) and 31,000 (G) and two minor subunits with Mrs of 26,000 and 28,000 all of which cross-react with antibody to Manduca ferritin. The 24 kDa subunit is the only one that is not glycosylated. Iron injections induce an increase in the proportion of the 24 kDa subunit. We conclude that Calpodes has ferritin and that it is glycosylated like mammalian serum ferritin.  相似文献   

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Li C  Li H  Su X  Li T 《Fish & shellfish immunology》2011,30(4-5):1147-1151
Ferritin, a major iron storage protein of most living organisms, plays a crucial role in iron metabolism. Here we reported the isolation and characterization of a cDNA of ferritin gene from Sinonovacula constricta (denoted as ScFER). The full-length cDNA of ScFER was of 996 bp, consisting of a 5'-UTR of 120 bp, a 3'-UTR of 360 bp, and a complete open reading frame of 516 bp encoding a polypeptide with 171 amino acid residues. The predicted molecular mass of deduced amino acid of ScFER was 19.76 kDa and the theoretical pI was 5.07. Quantitative real-time PCR was employed to analyze the expression profiles of ScFER mRNA in muscle, mantle and visceral mass after iron exposure. The peak expression level of ScFER in the three tissues was 1.79-fold, 1.31-fold and 3.51-fold increases in muscle, mantle and visceral mass, respectively. The polyclonal antibodies generated from the recombinant product of ScFER could be specifically identified not only the recombinant product, but also the native protein from muscle. All these results strongly suggested that ScFER was involved in the iron metabolism regulation in S. constricta.  相似文献   

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