Identifying phenotypic expansions for congenital diaphragmatic hernia plus (CDH+) using DECIPHER data

Congenital diaphragmatic hernia (CDH) can occur in isolation or in conjunction with other birth defects (CDH+). A molecular etiology can only be identified in a subset of CDH cases. This is due, in part, to an incomplete understanding of the genes that contribute to diaphragm development. Here, we used clinical and molecular data from 36 individuals with CDH+ who are cataloged in the DECIPHER database to identify genes that may play a role in diaphragm development and to discover new phenotypic expansions. Among this group, we identified individuals who carried putatively deleterious sequence or copy number variants affecting CREBBP, SMARCA4, UBA2, and USP9X. The role of these genes in diaphragm development was supported by their expression in the developing mouse diaphragm, their similarity to known CDH genes using data from a previously published and validated machine learning algorithm, and/or the presence of CDH in other individuals with their associated genetic disorders. Our results demonstrate how data from DECIPHER, and other public databases, can be used to identify new phenotypic expansions and suggest that CREBBP, SMARCA4, UBA2, and USP9X play a role in diaphragm development.

Identification of a caleosin associated with hazelnut (Corylus avellana L.) oil bodies

Caleosins are involved in several cellular and biological processes that are closely associated with the synthesis, degradation and stability of oil bodies (OB). Because of the importance and the multiple roles of these OB-associated proteins, in silico identification of sequences corresponding to putative caleosins in the hazelnut genome has been performed, and the association with seed OB was verified using a proteomic approach. Five full-length sequences (CavCLO-H1, CavCLO-H2, CavCLO-H3, CavCLO-L1, CavCLO-L2), belonging to the two groups of caleosins (H and L), have been identified in the hazelnut genome. The number of identified caleosins is in agreement with that previously observed in other plant species, confirming that caleosins comprise small gene families in plants. A proteomic approach allowed us to verify only the presence of CavCLO-H1 in hazelnut OB, suggesting that several members inside this family could have different roles during plant growth and development. In silico analysis also suggests that CavCLO-H1 may act as a peroxygenase.

A new case of SMABF2 diagnosed in stillbirth expands the prenatal presentation and mutational spectrum of ASCC1

Spinal muscular atrophy with congenital bone fractures 2 (SMABF2) is a rare autosomal recessive neuromuscular disorder characterized by arthrogryposis multiplex congenita and prenatal fractures of the long bones, with poor prognosis. The most affected patients present with biallelic loss-of-function nucleotide variants in ASCC1 gene, coding a subunit of the transcriptional coactivator ASC-1 complex, although the exact pathogenesis is yet unknown. This work describes the first case of SMABF2 in a stillbirth with documented evolution of the disease in the prenatal period. A microdeletion copy number variant (CNV) of about 64 Kb, involving four exons of ASCC1, was firstly detected by microarray analysis, requested for arthrogryposis and hydrops. Subsequent exome analysis disclosed a nucleotide variant of the same gene [c.1027C>T; (p. Arg343*)], resulting in the introduction of a premature termination codon. This stillbirth represents the first case of ASCC1 compound heterozygosity, due to an exonic microdeletion and a nucleotide variant, expanding the mutational spectrum of this gene. It also provides further evidence that exonic CNVs are an underestimated cause of disease-alleles and that the integrated use of the last generation genetic analysis tools, together with careful clinical evaluations, are fundamental for the characterization of rare diseases even in the prenatal setting.

Cloning, expression, and antigenic characterization of recombinant protein of Mycoplasma gallisepticum expressed in Escherichia coli

Mycoplasma gallisepticum (MG) is a member of the most important avian mycoplasmas, causing chronic respiratory disease in chickens and leading to important economic losses in the poultry industry. Recombinant technology represents a strategic approach used to achieve highly reliable and specific diagnostic tests in veterinary diseases control: in particular this aspect is crucial for confirming mycoplasma infection and for maintaining mycoplasma-free breeder flocks. In this study, we identified a component of the pyruvate dehydrogenase dihydrolipoamide acetyltransferase (i.e., E2) protein by 2-dimensional electrophoresis (2-DE), characterized it in immunoblotting assays, and analyzed its recombinant (r-E2) in a rec-ELISA test. For full-length protein expression in Escherichia coli (EC) a point mutation was introduced. A rabbit antiserum produced against r-E2 was tested in a Western Blot using different samples of Mycoplasma species. The results showed the applicability of site-directed mutagenesis, with a good yield of the r-E2 after purification. Also, anti-E2 serum reacted with all the tested MG strains showing no cross reaction with other mycoplasmas. The developed E2 ELISA test was capable of detecting MG antibodies in the sera examined. Those results demonstrate the antigenic stability of the E2 protein which could represent a recombinant antigen with potential diagnostic applications.

Shrimp allergy beyond Tropomyosin in Italy: clinical relevance of Arginine Kinase, Sarcoplasmic calcium binding protein and Hemocyanin

BACKGROUND

Little is known about the prevalence and clinical relevance of sensitization to shrimp allergens other than tropomyosin.

OBJECTIVE

We detected the prevalence of arginine kinase and sarcoplasmic calcium binding protein sensitization, and identified a high molecular weight allergen that is frequently recognized by Italian shrimp-allergic patients.

METHODS

Sera from 40 shrimp-allergic patients underwent the detection of IgE specific for arginine kinase (rPen m 2) and sarcoplasmic calcium-binding protein (rPen m 4) by ISAC 112 Microarray platform and immunoblot analysis. A high molecular weight shrimp allergen was identified by N-terminal amino acid sequencing.

RESULTS

IgE to rPen m 2 and rPen m 4 were found in 4/40 (10%) and 6/40 (15%) sera, respectively; two sera reacted to both allergens. Clinically, 6/8 Pen m 2 and/or Pen m 4 reactors experienced severe allergies to shrimp. On immunoblot, 4/6 rPen m 4-positive sera showed IgE reactivity at about 20 kDa, whereas no rPen m 2-positive serum reacted at about 40 kDa. Nineteen (47%) sera showed IgE reactivity at molecular weights > 60 kDa. Such profile was not associated with IgE reactivity to rPen m 2 or rPen m 4. N-terminal amino acid sequencing of the high molecular weight allergen led to the identification of hemocyanin.

CONCLUSION

Shrimp arginine kinase and sarcoplasmic calcium-binding protein are minor allergens sensitizing only 10%-15% of Italian shrimp-allergic patients, but are clinically relevant. Hemocyanin is a clinically relevant high molecular weight shrimp allergen possibly cross-reacting to house dust mite.

Combining LC-MS/MS, PMF and N-terminal amino acid sequencing for multiplexed characterization of a bacterial surfactant glycoprotein biosynthesized by Acinetobacter radioresistens S13

The present study has highlighted the mechanisms of bacterial protein glycosylation. Experimental results underline that the consensus sequon can be different from the one found in Eukarya.

Mugwort-fennel-allergy-syndrome associated with sensitization to an allergen homologous to Api g 5

BACKGROUND

The cross-reactive allergen responsible for the so called "mugwort-celery-spice-syndrome", a pollen-food allergy that occurs in a minority of mugwort pollen-allergic patients, is still undefined.

OBJECTIVE

To identify the allergen responsible for the cross-reactivity between mugwort pollen and plant-derived foods.

METHODS

The serum from one index patient with both fennel and mugwort pollen allergy was used to identify IgE-reactive allergens by direct ELISA and Immunoblot analysis. Cross-reactivity between mugwort pollen and fennel was checked by cross-inhibition experiments. Fennel and mugwort allergens selected on the basis of IgE reactivity and inhibition tests were excised from SDS-PAGE gels and microsequenced. The amino acid sequences obtained were used to screen the NCBI database using the protein BLAST software.

RESULTS

On ELISA inhibition experiments, serum absorption with fennel extract completely inhibited the IgE response to mugwort. On immmunoblot analysis periodate treatment caused the disappearance of all bands of IgE reactivity except one at about 60 kDa. The 60 kDa bands from both mugwort and fennel PAGE-SDS gels revealed the presence of distinct proteins. The N-terminal amino acid sequencing gave the same major amino acid sequence corresponding to an Api g 5-like allergen. The MS/MS spectra were analyzed and a provided evidence of a fennel-specific protein with sequence similarity to phosphoglyceromutase from Apium graveolens.

CONCLUSION

A 60 kDa allergen, highly homologous to Api g 5, was recognized in fennel by patient's IgE. Inhibition experiments showed a high degree of cross-reactivity between this fennel allergen and the homologous mugwort pollen allergen. This allergen might be responsible for the mugwort-celery-spice syndrome.

Fennel allergy is a lipid-transfer protein (LTP)-related food hypersensitivity associated with peach allergy

Fennel allergy has been rarely reported, and the association with peach allergy has never been described. Our aim was to (i) study the correlation between symptom severity of peach and fennel and (ii) identify fennel allergens and the role of rPru p 3 antibodies in severe reactions to fennel. In 148 patients with peach allergy, we investigated 58 patients with symptoms and IgE antibodies positive to fennel. IgE to rPru p 1, 3, and 4 and rBet v 1, 2, and 4 were measured by immunoblotting, and the N-terminal amino acid sequences and relevant allergens were determined. We found significant association between severe reactions to fennel and peach (p = 0.0009). A major allergen was ~9 kDa lipid-transfer protein (LTP), cross-reactive with Pru p 3, a 15 kDa protein identified as a pathogenesis-related protein 1 of the Bet v 1 family. In conclusion, peach and fennel severe allergic symptoms are significantly related, and LTP is a major fennel allergen. Fennel should be included in the LTP syndrome.

Prenatal diagnosis and molecular characterization of an interstitial 1q24.3-31.3 deletion: case report and review

We describe a foetus with an interstitial deletion of 1q detected in amniotic fluid cells and we review the literature of similar pre- and postnatal cases, in order to identify prognostic factors useful for prenatal counselling. Foetal/parents karyotyping and FISH with whole chromosome 1 paint and BAC clone specific for 1q23-32 region were performed. Further 100 Kb resolution array-CGH analysis was executed after pregnancy termination on DNA extracted from foetal skin fibroblasts. Cytogenetic analyses revealed a de novo interstitial deletion involving the long arm of chromosome 1. FISH analysis confirmed that the deletion involves the intermediate 1q31.2 region. Foetal ultrasound (US), performed at 21 weeks of gestation, showed intrauterine growth restriction, shortening of the long bones, echogenic intracardiac focus and mild cerebral ventriculomegaly. Array-CGH localized the deletion in a DNA sequence of about 21 Mb in the 1q24.3-q31.3 region. Our findings, together with available data on patients with 1q deletion, suggest that the most severe phenotypes are not simply associated with larger deletion, and that the results of prenatal US assessment, rather than a fine molecular characterization of the deletion, should be taken into account for prognostic evaluation.

Authentication of food allergen quality by physicochemical and immunological methods

Purified allergens are required to detect cross-contamination with other allergenic foods and to understand allergen interaction with other components of the food matrix. Pure allergens are also used for the diagnosis and treatment of food allergies. For example, serological methods are being developed to improve the quality of diagnosis, and to reduce the need for food challenge tests. In addition, recombinant allergens are being evaluated as candidate vaccines for safe and efficacious specific immunotherapy. Pure allergens are indispensable as reference materials for the calibration and standardization of methods between different laboratories and operators for risk assessment in the food industry. Therefore, there is a need for well-defined purified food allergens. In this context, a panel of 46 food allergens from plant and animal sources has been purified, from either the food sources or as recombinant forms, within the EU-funded EuroPrevall project. These allergens have been characterized by a battery of diagnostic tests demonstrating that they constitute an authentic, well-defined library of comparable quality. The review summarizes the applications, potentials and limitations of key techniques used for the characterization and authentication of these allergen preparations, with a special emphasis on protein purity and identity, folding, post-translational modifications and immunochemical properties. One key area identified is the development of powerful analytical techniques, such as mass spectrometry and nuclear magnetic resonance, to improve the authentication of allergens for routine applications in allergy management.

Olive oil adulterated with hazelnut oils: simulation to identify possible risks to allergic consumers

According to European Union Regulation EC 1531/2001, olive oil labelled as "extra-virgin" should be cold-pressed and contain no refined oil or oil from other oleaginous seeds or nuts. Adulteration of extra virgin olive oil (EVOO) with hazelnut oil (HAO) is a serious concern both for oil suppliers and consumers. The high degree of similarity between the two fats complicates the detection of low percentages of HAO in EVOO. Many analytical approaches have been developed in recent years to trace HAO in EVOO, principally based on chromatographic analyses, differential scanning calorimetry or nuclear magnetic resonance. In addition adulteration of EVOO with HAO may introduce hazelnut-derived allergens. The aim of this work was to analyse the protein and allergen content of EVOO intentionally spiked with raw cold-pressed HAO or solvent-extracted HAO. SDS-PAGE analysis confirmed the presence of hazelnut proteins in solvent-extracted HAO with molecular masses ranging 10-60 kDa. In contrast, cold-pressed HAO showed no traces of protein. In spiked EVOO, solvent-extracted HAO was still detectable at a 1% contamination level. Several bands on SDS-PAGE migrated at apparent molecular masses coinciding with known allergens, such as Cor a 1 (approximately 17 kDa), Cor a 2 (approximately 14 kDa), Cor a 8 (approximately 12 kDa), oleosin (approximately 17 kDa) and Cor a 9 (approximately 60 kDa). MALDI-TOF MS analysis confirmed the presence of two oleosin isoforms and of Cor a 9. Immunoblotting demonstrated that an allergic patient with known reactivity to Cor a 1 and Cor a 2 recognized a 17-kDa band in solvent-extracted HAO. In conclusion, we have shown that adulteration of extra virgin olive oil with solvent-extracted hazelnut oil can be traced by simple SDS-PAGE analysis, and that adulteration introduces a potential risk for hazelnut allergic patients.

Mare's colostrum globules stimulate fibroblast growth in vitro: a biochemical study

The wound repair function of mare's milk and colostrum was investigated. Mare's colostrum improved wound healing in vivo; thus fibroblast growth activation by mare's milk and colostrum was examined. As expected, colostrum was more effective than milk. To establish the biochemical nature of the bioactive molecules involved, colostrum was fractionated into whey, casein, and fat globules, and the efficacy of these fractions on fibroblast proliferation was studied. The fat globule fraction provided the strongest stimulation; its composition was studied and compared with the less-active milk fat globule fraction. The lipid pattern highlighted several differences between mare's colostrum and milk; in particular, total lipid, linoleic acid, linolenic acid, ganglioside, and glycolipid contents were higher in colostrum. A proteomic investigation revealed some differences between the protein composition of colostrum and milk fat globules. Adipophylin and lactadherin were significantly overexpressed in colostrum fat globules. The role of specific lipids on skin wound repair and that of the epidermal growth factor-like domain, embedded within the lactadherin molecule and probably released in conditions stimulating proteolysis, are discussed.

Autoantibody signature in human ductal pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by rapid progression, invasiveness, and resistance to treatment. It is the fourth leading cause of cancer death with a 2% 5-year survival rate. Biomarkers for its early detection are lacking. This study was designed to use a proteomics-based approach as a means of identifying antigens that elicit a humoral response in PDAC patients. Antibodies against PDAC-associated antigens are useful for early cancer diagnosis and therapy. Proteins from PDAC cell lines were separated by 2-DE, and the serum IgG reactivity of 70 PDAC patients, 40 healthy subjects (HS), 30 non-PDAC tumor patients, and 15 chronic pancreatitis (CP) patients was tested by Western blot analysis. Spots specifically recognized by PDAC sera and revealed by mass spectrometry corresponded to metabolic enzymes or cytoskeletal proteins. Most were up-regulated in PDAC tissues. Thus, it seems that metabolic enzymes and cytoskeletal proteins are specific targets of the humoral response during PDAC. The results of further studies of these serological-defined antigens could be of diagnostic and therapeutic significance in PDAC.

Degradation of aromatic compounds by Acinetobacter radioresistens S13: growth characteristics on single substrates and mixtures

Acinetobacter radioresistens S13 is able to grow on phenol or benzoate as the sole carbon and energy source: both these compounds are catabolized through the beta-ketoadipate pathway. Genes encoding the catabolic enzymes for degradation of aromatic compounds are localized on A. radioresistens S13 chromosome and organized in, at least, two distinct sets, one for benzoate degradation and another for phenol catabolism. In the present study, the growth and biodegradation kinetics for benzoate and phenol, and an easily metabolized substrate (acetate) were established. Benzoate was degraded slower and supports a less rapid and efficient growth than either acetate or phenol. A combined transcript-proteomic analysis of some of the major catabolic genes and their products nonetheless has shown that benzoate induces the expression of both benzoate and phenol catabolic operons. This result was confirmed by the fact that benzoate-acclimatized bacteria were rapidly able to degrade phenol too. Finally, the growth and biodegradation kinetics for different mixtures of acetate, benzoate and phenol were determined. Results indicate that a hierarchy of substrate utilization, benzoate > acetate > phenol, occurred: benzoate was the preferred substrate, despite its lower growth and biodegradation parameters. Hypotheses explaining these unusual metabolic features of A. radioresistens S13 are discussed.

Combined cup loading, bis(2-hydroxyethyl) disulfide, and protein precipitation protocols to improve the alkaline proteome ofLactobacillus hilgardii

Despite the large number of papers dealing with bacterial proteomes, very few include information about proteins with alkaline pI's, because of the limits inherent in 2-DE technology. Nonetheless, analyses of in silico proteomes of many prokaryotes show a bimodal distribution of their proteins based on their pI's; the most crowded areas lying between pI 4-7 and 9-11. The aim of the present research was to set up a general, simple, and standardizable 2-DE protocol suitable for studying the alkaline proteome of Lactobacillus hilgardii, a Gram-positive bacillus isolated from wine. The method has also been tested on a Gram-negative bacterium able to degrade aromatic pollutants, Acinetobacter radioresistens S13. Optimization of the method was mainly focused on improving protein extraction and IEF (pI 6-11) separation protocols. Concerning IEF, different methods for sample loading (in-gel rehydration and cup loading), and different reducing agents (DTT and bis(2-hydroxyethyl) disulfide (HED)) were tested and compared. The proposed protocol was found to resolve efficiently alkaline proteins from both of our Lactobacillus and Acinetobacter strains, in spite of their different external layers, thus, enabling a more comprehensive study of their proteomes.

Identification of latex UDP glucose pyrophosphorylase (Hev b UDPGP) as a novel cause of latex fruit allergy syndrome

Based on a recently published unusual ase of food allergy in a latex-allergic patients, the present study identifies Hev b UDPGP as a novel allergen in natural rubber latex able to cause latex-fruit allergy syndrome and as a novel, potential pan-allergen in vegetable foods.

Development of recombinant chimeric antigen expressing immunodominant B epitopes of Leishmania infantum for serodiagnosis of visceral leishmaniasis

Wild canids and domestic dogs are the main reservoir of zoonotic visceral leishmaniasis (VL) caused by Leishmania infantum (syn.: Leishmania chagasi). Serological diagnosis of VL is therefore important in both human and dog leishmaniasis from a clinical and epidemiological point of view. Routine diagnosis of VL is traditionally carried out by immunofluorescent antibody test (IFAT), which is laborious and difficult to standardize and to interpret. In the last decade, however, several specific antigens of Leishmania infantum have been characterized, allowing the development of a recombinant-based immunoassay. Among them, the whole open reading frame encoding K9 antigen, the gene fragment encoding the repetitive sequence of K26, and the 3'-terminal gene fragment of the kinesin-related protein (K39sub) were previously evaluated as diagnostic markers for canine leishmaniasis and proved to be independent in their antibody reactivity. Since sensitivity of serological test is usually higher in multiple-epitope format, in this study the relevant epitopes of K9, K26, and K39 antigens were joined by PCR strategy to produce the chimeric recombinant protein. The resulting mosaic antigen was found highly expressed in Escherichia coli and efficiently purified by affinity chromatography. Antigenic properties of this recombinant antigen were evaluated by indirect enzyme-linked immunosorbent assay (ELISA) using a panel of human and dog sera previously characterized by parasitological and/or serological techniques. Chimeric ELISA showed 99% specificity in both human (n = 180) and canine (n = 343) control groups, while sensitivity was higher in canine VL (96%, n = 213) than in human VL (82%, n = 185). Accordingly, concordance between IFAT and canine chimeric ELISA (k = 0.95, 95% confidence interval = 0.93 to 0.98) was higher than between IFAT and human chimeric ELISA (k = 0.81, 95% confidence interval = 0.76 to 0.87). Results suggest the potential use of this new antigen for routine serodiagnosis of VL in both human and canine hosts.

Novel isoforms of Pru av 1 with diverging immunoglobulin E binding properties identified by a synergistic combination of molecular biology and proteomics

Birch pollen-related food allergies are mainly associated to Bet v 1. Little is known about isoforms of Bet v 1 homologous in fruit of the Rosaceae family. We attempted to identify novel isoforms of Pru av 1, the major cherry allergen, at the cDNA and the protein level by a combination of molecular biology and proteomic tools. A cDNA library was screened with patients immunoglobulin E (IgE) and a specific hybridization probe. Edman sequencing, mass spectrometry (MS), and MS/MS were performed after detecting Pru av 1 on 2-D maps by immunoblotting using patients IgE and a monoclonal antibody. Partial amino acid sequences were completed with a polymerase chain reaction (PCR) strategy. The IgE-binding properties of the Pru av 1 spots were analyzed by 2-D blot inhibition. cDNA library analysis revealed a novel Pru av 1 isoform. MS and N-terminal sequencing confirmed the cDNA sequences at the protein level. A series of spots were confirmed as the already known Pru av 1. One spot, exclusively detected with patients sera, was identified as the novel isoform. A partial amino acid sequence detected with MS/MS was completed by PCR-cloning. The 2-D blot inhibition revealed epitope differences between the novel isoform and the previously published Pru av 1. Our data demonstrate that a synergistic combination of molecular biology and proteomics represents a powerful tool for reliable and comprehensive identification of allergen isoforms and variants. The newly identified isoform showed diverging IgE-binding properties and may be relevant for the diagnosis or therapy of cherry allergy.

The proteomic approach to analysis of human milk fat globule membrane

Lactating mammary epithelial cells do not adhere to the classical rule of lipid secretion since lipids are secreted enveloped by the milk fat globule membrane (MFGM) via a budding process. Historically, biochemical studies of MFGM proteins focused on the analysis of single molecules. Today, thanks to proteomic technologies, it is now possible to comprehensively analyse the protein component of MFGM. Questions concerning: (1) protein organization within the MFGM structure; (2) correlation to the intracellular secretion pathway; and (3) display of multiple specialized functions, can now be addressed. Proteomics allows for rapid identification of the total MFGM proteins thereby providing a global functional screen of the lactating cell. In addition to their nutritional value, human MFGM proteins have important protective functions against bacteria, viruses and protozoa. Identifying the complex nature of protein-protein interactions would further enhance our present knowledge of MFGM function. A speculative molecular architecture of the human MFGM is proposed.

Antigenic determinants of bovine serum albumin

BACKGROUND

Bovine serum albumin (BSA) is one of the most widely studied proteins; its structure is well known and its antigenic characteristics have been described in several papers. The aim of this research was the identification of the BSA antigenic determinants.

METHODS

This study was performed using limited proteolysis and an immunoblotting technique, in which a commercial murine antibody and sera from children sensitized to BSA were used.

RESULTS

Findings suggest amino acids (aa) 524-598 as an epitopic area for human species. The most critical sequence seems to be aa 524-542, even if it must be included in a longer fragment to be recognized by antibodies. Murine IgG antibodies also recognize fragments contained in the first half (NH(2)-terminal portion) of BSA.

CONCLUSIONS

The results presented in this study indicate that the epitopic sites of an antigenic protein can be different when different species are considered, so that data obtained with antibodies from animal species cannot be directly extrapolated to the behavior of human IgEs.

The catechol 1,2 dioxygenase system of Acinetobacter radioresistens: isoenzymes, inductors and gene localisation

Two different isozymes (Iso A and Iso B) of catechol 1,2 dioxygenase (C1,2O) were isolated from cultures of A. radioresistens grown in two different media, containing phenol and benzoate respectively. In the phenol medium the bacteria expressed about 90% of Iso A, whereas in the benzoate medium the Iso A/Iso B ratio was 40:60. The two proteins have different molecular masses, isoelectric points and N-terminal sequences that are not consistent with simple post-translational modifications. Furthermore, their behaviour differs at high temperatures (42 degrees C-47 degrees C) and at moderately acidic pH (pH 6.0): Iso A proved to be the more stable under conditions of environmental stress. Hybridisation analysis with an A. calcoaceticus catA-derived probe revealed that A. radioresistens C1,2O proteins are encoded by two chromosomally located genes. Bidimensional electrophoresis (2DE) maps of crude extracts of cells grown in different carbon sources (phenol, benzoate and acetate) clearly demonstrated a differential induction pattern for the two proteins. The hypothesis of a double set of genes, one for benzoate catabolism and the other for phenol catabolism, is discussed, and analogies are drawn with other known C1,2Os.

Characterization of the major allergen of plum as a lipid transfer protein

BACKGROUND

Allergy to Prunoideae fruit (plum, peach, cherry and apricot) is one of the most frequent food allergies in southern Europe. All these fruits cross-react in vivo and in vitro, as they share their major allergen, a 9 kD lipid transfer protein (LTP).

OBJECTIVE

The aim of the study was the identification and molecular characterization of the major allergen of plum.

METHODS

The IgE pattern of reactivity to plums was investigated by SDS-PAGE and immunoblotting with the sera of 23 patients. The identified major allergen was purified by HPLC, using a cationic-exchange column followed by gel-filtration. Further characterization was achieved by periodic-Schiff stain, isoelectrofocusing and N-terminal amino acid sequencing.

RESULTS AND CONCLUSIONS

The major allergen of plum is a 9 kD lipid transfer protein, not glycosylated and with a basic character (pI>9), highly homologous to the major allergen of peach.

Determination of the primary structure of two lipid transfer proteins from apricot (Prunus armeniaca)

It has been recently demonstrated that the major allergen of apricot is a protein of molecular mass (Mr) 9000 belonging to the family of Lipid Transfer Protein. The aim of this study was the determination of the primary structure of apricot LTP by micro-sequencing and mass spectrometric analyses. Apricot LTP is a 91 amino acids protein like peach and almond LTPs with a sequence identity of 91% and 94%, respectively. Like for the peach LTP, out of the 25 amino acids forming the inner surface of the tunnel-like hydrophobic cavity in maize ns-LTP, 16 are identical and 7 similar in the apricot LTP, supporting the hypothesis of a similar function.

The major allergen of sesame seeds (Sesamum indicum) is a 2S albumin

BACKGROUND

Allergic reactions induced by ingestion of foods containing sesame seeds are a well recognized cause of severe food-induced anaphylaxis.

OBJECTIVE

This study aimed to identify and characterize the clinically most important major allergen of sesame seeds.

METHODS

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and IgE immunoblotting were performed on sera of 10 patients selected for severe and documented allergic reaction after eating food containing sesame. The major allergen was purified by gel filtration and characterized by isoelectric point (pI), glycosylation and amino acid sequencing.

RESULTS

All the patients had positive IgE antibodies and skin prick tests (SPTs) to sesame. The major, clinically most important allergen was a protein with molecular mass of about 9000. It was not glycosylated, the amino acid sequence showed it was a 2S albumin with a pI of 7.3; the small and the large subunits, forming the whole protein, showed pI values of 6.5 and 6.0.

Human proteome enhancement: high-recovery method and improved two-dimensional map of colostral fat globule membrane proteins

The human milk fat globule membrane protein composition is still largely unknown, although it counts for 2-4% of the total milk protein content and contains several important biologically active components. The aim of this work was to create a two-dimensional electrophoresis (2-DE) map of the human milk fat globule membrane proteins, both integral and membrane-associated, and to identify and characterize as many protein components as possible. A new protocol for the solubilization and extraction of the human milk fat globule membrane proteins with a double extraction procedure is presented, and the results compared with the extraction methods reported in the literature. The proteins were separated, in the first dimension, by isoelectric focusing (IEF) in the pH range 3-10 on strips of 13 cm length and, in the second dimension, by Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) on 11.5% T homogeneous gels. A reproducible 2-DE map of integral and membrane-associated proteins was obtained and the first 23 spots, representing the major components, were identified by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometric analysis and/or by amino acid sequencing.

Media containing aromatic compounds induce peculiar proteins in Acinetobacter radioresistens, as revealed by proteome analysis

An Acinetobacter radioresistens strain able to grow on phenol or benzoate as sole carbon and energy source through the beta-ketoadipate pathway was isolated in our laboratories. In previous research, we found a different expression of catechol-1,2-dioxygenase isoenzymes (C-1,2-O) depending on the growth substrate (phenol or benzoate). In the present study, we used proteome techniques to extend our investigation to other enzymes involved in the aromatic degradation pathway. Since the first nontoxic metabolite in this route is cis,cis-muconic acid, we focused our attention on the enzymes leading to this compound, chiefly phenol hydroxylase (PH), benzoate dioxygenase (BD), cis-1,2-dihydroxycyclohexa-3,5-diene-1-carboxylate dehydrogenase (D) and C-1,2-O. In particular, the A. radioresistens proteome was monitored under different growth substrate conditions, using acetate, benzoate, or phenol as sole carbon source. We compared the protein maps by software image analysis and detected marked differences, suggesting the inducibility of most enzymes. This research also sought to evaluate the conditions allowing the best expression of enzymes to be used in immobilized systems suitable for bioremediation. The experimental data indicate that benzoate is the best carbon source to gain the highest amount of C-1,2-O and D, while phenol is the best growth substrate to obtain PH.

Proteolysis of beta-casein as a marker of Grana Padano cheese ripening

Proteolysis has a critical role in defining the typical organoleptic characteristics of Grana Padano, a well-known Italian cheese. During the ripening process, hydrolysis of beta-casein produces different fragments, the most abundant and widely studied of which are gamma-caseins, three polypeptides containing the HOOC-terminal portion of beta-casein. By sodium dodecyl sulfate-PAGE and a specific anti-beta-casein monoclonal antibody, two beta-casein-derived bands were identified in Grana Padano cheese: betaa and betab. Thanks to the identification of the amino acid sequences, it was shown that: a) betaa contains gamma1-casein [beta-casein (29-209)] and the correlated peptide [beta-casein (30-209)]; b) betab contains gamma2-casein [beta-casein (106-209)] and gamma3-casein [beta-casein (108-209)]. The production of betaa and betab by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. A significant correlation between abundance of some polypeptides and ripening process was shown.

Proteolysis of alphas-casein as a marker of Grana Padano cheese ripening

Since casein proteolysis has a critical role in defining the typical characteristics of Grana Padano cheese, we evaluated the hydrolysis of alphas-casein during the ripening process. Thanks to the high specificity of the anti-alphas((alphas1 + alphas2)-casein monoclonal antibody and amino acid sequence determination, it was possible to identify three main alphas-casein-derived polypeptides in cheese: alphaa, alphab, and alphac. Their production by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. Data showed that alphaa was released in cheese mainly by the chymosin attack, while alphab and alphac were due to the action of plasmin. A significant correlation between the abundance of some polypeptides and ripening process was shown.

The maize major allergen, which is responsible for food-induced allergic reactions, is a lipid transfer protein

BACKGROUND

Cereals are the most important nutritional component in the human diet. Food-induced allergic reactions to these substances therefore have serious implications, and exhaustive diagnosis is required. Such diagnosis is still difficult because of the incomplete knowledge about major cereal allergens. In particular, few food-induced allergic reactions to maize have been reported, and no information on the allergenic proteins is available.

OBJECTIVE

Having observed several anaphylactic reactions to maize, we planned a study to identify maize major allergens and cross-reactivity with other cereals, as well as to peach because the majority of patients also reacted to Prunoideae fruits.

METHODS

Twenty-two patients with systemic symptoms after maize ingestion and positive skin prick test responses and serum-specific IgE antibodies to maize were selected. The IgE-reactivity pattern was identified by SDS-PAGE and immunoblotting. The major allergen identified was then purified by HPLC and characterized by mass spectrometry, determination of the isoelectric point value, and N-terminal amino acid sequencing.

RESULTS

Sera from 19 (86%) of the 22 patients recognized a 9-kd protein, thus confirming this as the maize major allergen. This protein had an isoelectric point of greater than 9, a molecular mass of 9047.0 d, and no glycosylation. Determination of its N-terminal sequence showed that it was a lipid transfer protein (LTP). By using immunoblotting-inhibition experiments, we demonstrated that the LTP cross-reacts completely with rice and peach LTPs but not with wheat or barley LTPs. N-terminal sequence of the 16-kd allergen (recognized by 36% of patients) showed it to be the maize inhibitor of trypsin. This protein cross-reacts completely with grass, wheat, barley, and rice trypsin inhibitors.

CONCLUSION

The major allergen of maize is an LTP with a molecular weight of 9 kd that is highly homologous with the peach LTP, the major allergen of the Prunoideae subfamily.

Identification of the human beta-casein C-terminal fragments that specifically bind to purified antibodies to bovine beta-lactoglobulin

The presence of foreign proteins in human milk after the ingestion of bovine dairy products is thought to be one of the possible causes of allergic sensitization in exclusively breast-fed predisposed infants. The immunologic determination of bovine beta-lactoglobulin (LG) concentration in human milk has been reported by several researchers, but the results are conflicting. Moreover, a strong cross-reactivity between antibodies to bovine beta-LG and human milk proteins and peptides was reported, throwing doubt on the reliability of radioimmunoassay and enzyme-linked immunosorbent assay detection and quantification assays for bovine beta-LG in human milk. Thus, the goal of this study was to isolate human milk peptides with a molecular mass >or= 1,000 Da cross-reactive with antibodies to bovine beta-LG in order to identify possible common epitopes between human and bovine milk proteins. The proteins were first isolated by affinity chromatography with purified polyclonal antibodies to bovine beta-LG, followed by gel filtration fast phase liquid chromatography and reverse phase-high performance liquid chromatography purification of the components specifically bound in the affinity separation step. Affinity-bound peptides were identified by determining their amino acid sequence. All the sequenced peptides belonged to the C-terminal part of human beta-casein, which confirms the cross-reactivity of human milk proteins and peptides with antibodies to bovine beta-LG and allows the identification of possible common epitopes between the two proteins. No bovine beta-LG peptides with a molecular mass >or= 1,000 Da were found in our milk samples from healthy mothers on a diet rich in bovine milk and dairy products.

Clinical role of a lipid transfer protein that acts as a new apple-specific allergen

BACKGROUND

Allergy to apple is commonly associated with birch pollinosis because the two share homologous allergens. However, some patients have apple allergy but no birch pollinosis, suggesting that there are allergens that do not cross-react with birch.

OBJECTIVE

The aim of the study was to evaluate the IgE reactivity pattern to an apple extract in subjects with allergic reactions to apple, with and without birch hay fever.

METHODS

Forty-three patients with oral allergy syndrome for apple and positive open food challenge, skin prick test, and serum specific IgE antibodies to apple were admitted to the study. Thirty-two had birch pollinosis (documented by specific IgE for birch) and 11 were not allergic to birch. The IgE reactivity pattern to apple extract was identified by SDS-PAGE and immunoblotting. The consistent allergen, a 9-kd protein, was then purified by HPLC and characterized by periodic acid-Schiff staining, isoelectric point, and N-terminal amino acid sequencing.

RESULTS

The sera from 28% of patients allergic to apple with birch pollinosis, but from all patients allergic only to apple, recognized the 9-kd protein. This protein has an isoelectric point of 7.5 and is not glycosylated. Determination of its partial amino acid sequence showed that it belongs to the family of lipid transfer proteins, which act as major allergens in Prunoideae fruits.

CONCLUSIONS

These results indicate that a lipid transfer protein is an important allergen in patients allergic to apple but not to birch pollen. The prevalent IgE reactivity to this allergen in subjects with no birch pollinosis and the physicochemical characteristics of this protein suggest that sensitization may occur through the oral route.

Complete amino acid sequence determination of the major allergen of peach (Prunus persica) Pru p 1

The major protein allergen of peach (Prunus persica), Pru p 1, has recently been identified as a lipid transfer protein (LTP). The complete primary structure of Pru p 1, obtained by direct amino acid sequence and liquid chromatography-mass spectrometry (LC-MS) analyses with the purified protein, is described here. The protein consists of 91 amino acids with a calculated molecular mass of 9178 Da. The amino acid sequence contains eight strictly conserved cysteines, as do all known LTPs, but secondary structure predictions failed to classify the peach 9 kDa protein as an 'all-alpha type', due to the high frequency of amino acids (nine prolines) disrupting alpha helices. Although the sequence similarity with maize LTP is only 63%, out of the 25 amino acids forming the inner surface of the tunnel-like hydrophobic cavity in maize ns-LTP 16 are identical and 7 similar in the peach homolog, supporting the hypothesis of a similar function.

Multiple forms of lactadherin (breast antigen BA46) and butyrophilin are secreted into human milk as major components of milk fat globule membrane

In the lactating mammary gland, epithelial cells secrete triacylglycerols in the form of droplets enveloped by an apical surface membrane. This membrane is known as the milk fat globule membrane (MFGM; Mather & Keenan, 1983). MFGM-associated proteins have been studied and employed in developing antibodies against surface antigens of breast epithelial cells, which are used in breast cancer immunodiagnosis and histopathology (Salinas et al. 1987; Larocca et al. 1991; Peterson et al. 1995). So far, only a small number of proteins have been analysed and their sequence identified in bovine, murine and human MFGM; among them are butyrophilin (Jack & Mather, 1990; Ishii et al. 1995; Taylor et al. 1996), MFG-E8 (Stubbs et al. 1990), PAS 6/7 (Hvarregaard et al. 1996) and lactadherin or breast antigen BA46 (Couto et al. 1996; Taylor et al. 1997). Several minor proteins have yet to be characterized, since it is not easy to isolate them in large quantities from the membrane. SDS gel patterns give useful information about MFGM proteins, such as concentration, relative molecular mass and presence of carbohydrate. Over forty membrane components have been separated by electrophoretic techniques from bovine MFGM (Mather et al. 1980).

The research reported here combined SDS-PAGE with sequencing analysis and describes the composition of human MFGM, with the exception of high molecular mass mucin, which only penetrates an acrylamide gel of 40 g/l. Mucins have been extensively studied and the sequence predicted from cDNA (Gendler et al. 1990). Surprisingly, identification of the protein bands in the present study revealed that three proteins alone constituted the major components of human MFGM: xanthine oxidase (EC 1.1.3.22), butyrophilin and lactadherin. Lactadherin belongs to a family of proteins possessing epidermal growth factor-like and factor V/VIII C1/C2-like domains, including bovine PAS 6/7, guinea pig GP55 (Hvarregaard et al. 1996) and murine MFG-E8 (Stubbs et al. 1990). In a previous investigation, we characterized lactadherin (formerly breast antigen BA46) and its truncated 30 kDa form as components of healthy human MFGM (Giuffrida et al. 1998). Human butyrophilin has recently been cloned and sequenced (Taylor et al. 1996); the presence of two extracellular immunoglobulin superfamily domains suggested a potential cell surface receptor function. This study was aimed at identifying and characterizing the multiple forms of the major proteins of MFGM.

Absence in human milk of bovine beta-lactoglobulin ingested by the mother. Unreliability of ELISA measurements

OBJECTIVES

To analyze the presence of bovine beta-LG in breast milk.

METHODS

Human milk samples from 14 healthy non-atopic women on diets with different cow's milk contents were examined. The total concentration of beta-LG immuno-like proteins (beta-LGIP) was determined by enzyme linked immunosorbent assay (ELISA). Identification of antigens was done by N-terminal sequencing.

RESULTS

beta-LGIP reactivity of the milk from subjects on different diets was not significantly different. Human lactoferrin, beta-casein and alpha-lactalbumin, were identified as cross-reacting antigens.

CONCLUSIONS

False-positive results in ELISA determinations of bovine beta-LG in human milk might be due to cross-reactions between polyclonal antibodies and different protein antigens.

Evidence for a common epitope between bovine alpha-lactalbumin and beta-lactoglobulin

The aim of this work was to check and quantify any cross-reactivities among the main bovine whey proteins, utilizing purified polyclonal antibodies against bovine beta-lactoglobulin, alpha-lactalbumin and serum albumin, and to identify possible common epitope(s). Purified polyclonal anti-bovine beta-lactoglobulin antibodies show 10% cross-reactivity with bovine alpha-lactalbumin, both in its native and its denatured form. A continuous stretch of four amino acids common to alpha-lactalbumin and beta-lactoglobulin that might be responsible for this cross-reactivity has been identified. Cross-reactivity between this antibody and bovine serum albumin is, on the contrary, negligible. Purified polyclonal anti-bovine alpha-lactalbumin and anti-serum albumin antibodies do not cross-react.

Identification of actinidin as the major allergen of kiwi fruit

BACKGROUND

Allergic reactions to fruits and vegetables are among the most frequent food allergies in adults. Kiwi fruit (Actinidia chinensis) is commonly involved, causing local mucosal, systemic, or both types of symptoms by an IgE-mediated mechanism. In a previous study on 30 patients allergic to kiwi, we identified a major allergen of 30 kd against which all sera tested clearly reacted. Other allergens were detected at 12, 24, and 28 kd.

OBJECTIVE

The aim of this study was to fully characterize the major kiwi fruit allergen of 30 kd.

METHODS

Allergens were separated and purified by high-performance liquid chromatography with anion-exchange columns. The purity of the single proteins was checked by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and their allergenicity was checked by immunoblotting with a pool of sera from patients allergic to kiwi. The allergens were characterized by isoelectrofocusing and amino acid sequencing, and periodic acid-Schiff stain was used to detect glycoproteins.

RESULTS

Proteins of 30, 28, 24, and 17 kd were purified by high-performance liquid chromatography. IgE binding indicated the 30 kd protein, which showed an isoelectric point of 3.5, as the major allergen of kiwi. Determination of its partial amino acid sequence and comparison with the Swiss Protein Bank showed that this was actinidin, the main protein component of kiwi. The 24 and 28 kd proteins had the same N-terminal sequence, which did not correspond to any known protein. The 17 kd protein had a blocked N-terminal sequence.

CONCLUSIONS

These results demonstrate that the major allergen of kiwi fruit, Act c 1, is actinidin, a proteolytic enzyme belonging to the class of thiol-proteases. Two other allergens of 24 and 28 kd appear identical on amino acid sequencing.

Isolation and characterization of full and truncated forms of human breast carcinoma protein BA46 from human milk fat globule membranes

We have isolated and characterized two proteins of 50 and 30 kDa from human milk fat globule membranes of healthy donors. N-terminal and internal sequencing revealed that the 50-kDa protein is the full-length human breast carcinoma protein BA46 that is highly expressed in human breast tumors. The 30-kDa protein is a truncated form of protein BA46 which consists of the C-terminal factor V/VIII-like domain of BA46 and which appears to anchor BA46 to the milk fat globule membrane. Defective release of the epidermal growth factor domain containing a surface RGD motif may be related to involvement of BA46 in breast cancer.

The unusual amino acid triplet Asn-Ile-Cys is a glycosylation consensus site in human alpha-lactalbumin

Human alpha-lactalbumin has not been described as a glycoprotein, despite the fact that several alpha-lactalbumins of both ruminant and nonruminant species are known to be glycosylated. In all these species the glycosylation site is the 45Asn in the usual triplet 45Asn-Gly/Gln-47Ser. We have found that human alpha-lactalbumin is glycosylated and the glycosylation site has been determined by protein sequencing and mass spectrometry. We report an unusual glycosylation site at 71Asn in the triplet 71Asn-Ile-73Cys, which is conserved in all known alpha-lactalbumins except red-necked wallaby. That a relatively small proportion of the protein is glycosylated (about 1%) may reflect the importance of this region of the protein sequence to the molten globule state of alpha-lactalbumin.

Detection of specific IgE to human milk proteins in sera of atopic infants

Specific IgE (sIgE) for cow's milk proteins (CMP) have been reported to be present in blood sera of exclusively breast-fed infants. The aim of this study was to find whether the presence of sIgE to human milk proteins in the sera of exclusively breast-fed infants could explain the apparent detection of sIgE to CMP in infants that were never previously in contact with cow's milk. sIgE for human milk whey proteins were found in the blood sera of atopic infants, and these sIgE strongly cross-reacted with the corresponding CMP. In none of the sera examined were sIgE to bovine beta-lactoglobulin detected.

Amino acid sequence and crystal structure of buffalo alpha-lactalbumin

Isolation, purification, amino acid sequence determination and X-ray crystal structure of buffalo alpha-lactalbumin were performed in order to gain further knowledge of the molecular basis of alpha-lactalbumin in the lactose synthase complex. The deduced amino acid sequence differs at one position from the bovine alpha-lactalbumin sequence (at position 17). The refined crystal structure at 2.3 A is very similar to those previously reported for human and baboon alpha-lactalbumins. However, a portion of the molecule (residues 105-109) exhibits different conformation. It forms a 'flexible loop', and appears to be a functionally important region in forming the lactose synthase complex.

Isolation of a new ligand-carrying casein fragment from bovine mammary gland microsomes

Whilst looking for components involved in retinol metabolism in secreting mammary gland cells, a 12 kDa protein was isolated. This protein had bound a ligand with characteristics of retinol. N-Terminal sequencing and amino acid analysis showed that this protein is highly homologous with an alpha-s1-casein fragment. No ligand was found for beta-lactoglobulin, previously thought to be involved in retinol metabolism.

Human milk components cross-reacting with antibodies against bovine beta-lactoglobulin

The human whey components cross-reacting with antibodies raised against bovine and/or equine beta-lactoglobulin were screened systematically. The milk of six women on a normal diet was collected within 72 h of confinement and whey components were fractionated by high-speed size exclusion chromatography and reversed-phase techniques. The fractions which were immunoreactive in double diffusion experiments with antisera anti-bovine and/or equine beta-lactoglobulin were subsequently purified by native PAGE and then electroblotted on Pro-blott membrane (Western blotting). Pro-blot membranes were stained in parallel with Coomassie and by immunostaining using antibodies against bovine and/or equine beta-lactoglobulin as first antibody solution. The immunoreactive bands were cut out from the membrane and N-terminally sequenced; all the immunoreactive components were clearly identified as human beta-casein or its (mainly tryptic) fragments. The strong antigenic similarity between human beta-casein and beta-lactoglobulin (bovine and equine) might be of immunological importance; it could mean that breast-fed neonates risk being sensitized to beta-lactoglobulin irrespective of the presence of cow's milk in the mother's diet.

Direct identification and characterization of llama (Lama glama L.) whey proteins by microsequencing after western blotting

Amino acid sequence determination is the most reliable and powerful tool to identify a protein or to classify a new one by comparison of its primary structure with already known sequences. A rapid and simple purification procedure is an essential pre-requisite for routine sequence determination. Structural characterization of llama whey proteins was undertaken for evolutionary as well as economic purposes. N-terminal sequence analyses directly on an immobilon polyvinylidene difluoride (PVDF) membrane, following Western blotting of both native and SDS-denatured llama whey proteins after polyacrylamide gel electrophoresis, revealed three different forms of glycosylated alpha-lactalbumin, and a protein with a high degree of homology with a camel whey protein of unknown function. Furthermore, by immunoblotting techniques, the electrophoretic band corresponding to serum albumin was identified.