Albumins Research Articles

Diagnostic Accuracy of Lipid Transfer Proteins (LTPs) Specific IgE Assay in Food Allergy: A Systematic Review

The aim of this systematic review was to evaluate the diagnostic accuracy of molecular-based LTPs serum sIgE for the diagnosis of food allergies in patients with suspected allergy to one of the LTPs-containing foods. Cohort, prospective or retrospective cross-sectional studies were considered for inclusion in this review. Oral food challenge (both open and double-blind placebo-controlled) was the reference standard for the diagnosis. PubMed (MEDLINE), Web of Science, Scopus, and ClinicalTrial.org were searched for relevant papers. The risk of bias was assigned by the QUADAS-2 tool. Data were reported as the sensitivity and specificity. The study protocol was registered in the PROSPERO database (CRD42022321985). Fifteen articles, including 2395 individuals, were included. The sensitivity of Ara h 9 for peanut allergy diagnosis ranged from 6 to 61%; the specificity ranged from 57 to 100%. The Cor a 8 sensitivity ranged from 11 to 43%, with the specificity ranging from 59 to 94%. Ara h 9 and Cor a 8 serum sIgE may be useful for confirming the diagnosis of peanut and hazelnut allergy in symptomatic patients, although the diagnostic accuracy is limited by the low sensitivity. More investigation on other LTPs and in adult populations may be important to define the clinical role of this test in food allergy diagnostics.

Co-opted ATG2 lipid transfer protein delivers phospholipids for biogenesis of viral replication organelles

Co-opted ATG2 lipid transfer protein delivers phospholipids for biogenesis of viral replication organelles

The transcription factor GhMYB4 represses lipid transfer and sucrose transporter genes and inhibits fiber cell elongation in cotton.

Cotton (Gossypium hirsutum) fiber is a highly elongated single cell with a thickened cell wall. MYB transcription factors are important regulators of plant cell elongation; however, the molecular mechanism involved in regulating fiber elongation remains to be explored. Here, we present evidence that the R2R3-MYB transcription factor GhMYB4 negatively regulates cotton fiber cell elongation by suppressing the expression of two crucial genes previously reported to affect fiber development: lipid transfer protein 4 (GhLTP4) and sucrose transporter 12 (GhSWEET12). GhMYB4 is preferentially expressed in elongating fiber cells. Knockdown of GhMYB4 in cotton results in longer fiber cells, whereas overexpression of GhMYB4 in Arabidopsis leads to reduced plant height and root length. Transcriptomic and lipidomic analyses revealed that GhMYB4 is involved in coordinating three interconnected biological processes, namely lipid content regulation, auxin signaling, and sugar metabolism. Additionally, we showed that GhMYB4 inhibits the expression of GhLTP4 and GhSWEET12 by binding to the MYB cis-element (TTTAGTG) in their respective promoters. Interestingly, bHLH transcription factor 105 (GhbHLH105) and MYB transcription factor 212 (GhMYB212) counteract the inhibitory effects of GhMYB4 on the expression of GhLTP4 and GhSWEET12, respectively. These findings provide insights into the complex molecular mechanisms regulating plant cell elongation.

Non-Specific Lipid Transfer Protein StLTP6 Promotes Virus Infection by Inhibiting Jasmonic Acid Signalling Pathway in Response to PVS TGB1.

Plant viruses rely on host factors for successful infection. Non-specific lipid transfer proteins (nsLTPs) play critical roles in plant-pathogen interactions; however, their functions and underlying molecular mechanisms in viral infections remain largely unknown. Jasmonic acid (JA) is a crucial regulatory hormone in the process of plant resistance to viral infection. In this study, we screened and verified that StLTP6, a previously identified pro-viral factor, interacts with the silencing suppressor triple gene block1 (TGB1) of potato virus S (PVS). The PVS TGB1 induces the expression of StLTP6, and both co-localize in the cytoplasm. Furthermore, StLTP6 interacts with allene oxide cyclase and inhibits its accumulation, thereby suppressing JA synthesis and attenuating RNA silencing antiviral resistance. In summary, we elucidated the molecular mechanism by which PVS TGB1 interacts with StLTP6 to facilitate PVS infection. These findings broaden our understanding of the biological roles of nsLTPs and provide a new antiviral target for potato research.

Exploring the pathophysiological mechanisms and wet biomarkers of VPS13A disease

VPS13A disease (also known as Chorea-Acanthocytosis, ChAc) is a representative subtype of the neuroacanthocytosis (NA) syndromes, characterized by neurodegeneration in the central nervous system and acanthocytosis in peripheral blood. It is a rare autosomal recessive genetic disorder caused by loss-of-function variants in the VPS13A gene, which is currently the only known pathogenic gene for ChAc. VPS13A protein is a member of novel bridge-like lipid transfer proteins family located at membrane contact sites, forming direct channels for lipid transport. The specific mechanism underlying how the loss of VPS13A function leads to the hematological and neurological phenotypes of the disease remains unclear. Here we present a review of recent studies on VPS13A protein and ChAc, focusing on the potential role of the VPS13A protein in pathophysiology of ChAc and also review the known and potential wet biomarkers of ChAc to enhance our comprehension of this rare disease.

Allergy to Plant-Based Panallergens LTPs in Children: A Scoping Review

Introduction: Lipid Transfer Proteins (LTPs) are plant-derived panallergens that have emerged as significant allergens in Mediterranean populations. Though less common in children, LTP allergies represent a critical consideration for physicians diagnosing plant food allergies in this demographic. Methodology: PRISMA-ScR guidelines were followed. A search with specific terms was performed in searchable databases. Two of the authors extracted and evaluated the data. Results: A total of 21 original studies and 6 case reports focusing on LTP allergies in the paediatric population met the inclusion criteria. Diagnostic tools, predictive markers and management options for LTP allergies were examined. Allergens, clinical presentation and history were the diagnostic tools investigated. The clinical and laboratory phenotypes of the patient were considered possible predictive markers for the evaluation and progression of LTP allergies. Lastly, dietary modifications and sublingual immunotherapy were identified as the main focus of LTP allergy management. Discussion: A summary of the results is presented, and at the same time, questions concerning the nature of LTP allergies and their management are raised. Conclusions: LTP allergy in children is something physicians should be aware of. Further research is needed to establish the differences in LTP allergies in children and adults and the effectiveness of immunotherapy in paediatric populations.

Live-Cell Identification of Inhibitors of the Lipid Transfer Protein CERT Using Nanoluciferase Bioluminescence Resonance Energy Transfer (NanoBRET).

A BRET system is described, in which Nanoluciferase was fused to the lipid transfer protein CERT for efficient energy transfer to a Nile red-labeled ceramide, which is either directly bound to CERT or transported to the adjacent Golgi membrane. Bulk formation of sphingomyelin, a major plasma membrane component in mammals, is dependent on CERT-mediated transfer of its predecessor ceramide. CERT is considered a promising drug target but no direct cell-based methods exist to efficiently identify inhibitors. The utility of the method was demonstrated by a library of 140 derivatives of the CERT inhibitor HPA-12. These were obtained in a combinatorial synthesis using solid-phase transacylation. Screening of the library led to six compounds that were picked and confirmed to be superior to HPA-12 in a subsequent dose-response study and also in an orthogonal lipidomics analysis.

Lebendzell‐Identifizierung von Inhibitoren des Lipid‐Transfer Proteins CERT Mithilfe von Nanoluciferase Bioluminescence Resonance Energy Transfer (NanoBRET)

AbstractEs wird ein BRET‐System beschrieben, für das Nanoluciferase mit dem Lipidtransferprotein CERT fusioniert wurde. Dadurch wird ein effizienter Energietransfer auf ein mit Nilrot markiertes Ceramid ermöglicht, das entweder direkt an CERT gebunden oder zur benachbarten Golgi‐Membran transportiert wird. Der CERT‐vermittelte Transfer des Intermediats Ceramid ist Voraussetzung für die Bildung von Sphingomyelin, einer wichtigen Plasmamembrankomponente bei Säugetieren. CERT gilt als vielversprechende Zielstruktur für Medikamente, jedoch gibt es keine direkten zellbasierten Methoden zur effizienten Identifizierung von Inhibitoren. Der Nutzen der hier entwickelten Methode wurde anhand einer Bibliothek von 140 Derivaten des CERT‐Inhibitors HPA‐12 demonstriert. Diese wurden in einer kombinatorischen Synthese mittels Festphasen‐Transacylierung gewonnen. Das Screening der Bibliothek führte zur Identifizierung von sechs Verbindungen, die in einer Dosis‐Wirkungs‐Studie sowie in einer orthogonalen Lipidomics‐Analyse als dem HPA‐12 überlegen bestätigt wurden.

Deciphering the mechanism underlying poor aqueous solubility of extracted quinoa proteins

This study aimed to decipher the mechanisms underlying poor solubility of quinoa proteins by investigating the form of quinoa proteins dispersed in water and how protein-protein interactions influenced the kinetic stability of proteins in the dispersions. Specifically, the relative solubility and the forms of quinoa proteins in 1–5 w/w% protein dispersions were determined by separating proteins via centrifugation and/or ultrafiltration. The kinetic stability of quinoa proteins in the supernatants over a 3-week storage period was characterized by determining the changes of concentration, composition and physicochemical properties of quinoa proteins and predicting protein-protein interactions. The results showed that quinoa proteins existed mainly as differently-sized protein aggregates in the dispersions, leading to low relative solubility. The coagulation of protein aggregates in the supernatants caused severe precipitation during the first week of storage whereas they were disassociated simultaneously. With further storage, the remaining proteins in the supernatants reached kinetic stability, which was contributed by stronger electrostatic repulsion and lower surface hydrophobicity. Moreover, 11S globulin and 2S albumin were precipitated and solubilized together during storage, which was ascribed to intermolecular interactions driven by multiple sites between 11S globulin and/or 2S albumin. This study lays a foundation for extensive utilization of quinoa proteins.

Making lipids very unhappy to discover how they bind to proteins.

Membrane lipid composition is maintained by conserved lipid transfer proteins, but computational approaches to study their lipid-binding mechanisms are limiting. Srinivasan et al. (https://doi.org/10.1083/jcb.202312055) develop a clever molecular dynamics simulations assay to accurately model lipid-binding poses in lipid transfer proteins.

Bridge-like lipid transfer protein 3A (BLTP3A) is associated with membranes of the late endocytic pathway and is an effector of CASM.

Recent studies have identified a family of rod-shaped proteins which includes VPS13 and ATG2 and are thought to mediate unidirectional lipid transport at intracellular membrane contacts by a bridge-like mechanism. Here, we show that one such protein, BLTP3A/UHRF1BP1, associates with VAMP7-positive vesicles via its C-terminal region and anchors them to lysosomes via the binding of its chorein domain containing N-terminal region to Rab7. Upon damage of lysosomal membranes and resulting mATG8 recruitment to their surface by CASM, BLTP3A first dissociates from lysosomes but then reassociates with them via an interaction of its LIR motif with mATG8. Such interaction is mutually exclusive to the binding of BLTP3A to vesicles and leaves its N-terminal chorein domain, i.e. the proposed entry site of lipids into this family of proteins, available for binding to another membrane, possibly the ER. Our findings reveal that BLTP3A is an effector CASM, potentially as part of a mechanism to help repair or minimize lysosome damage by delivering lipids.

Insights into the functional mechanism of the non-specific lipid transfer protein nsLTP in Kalanchoe fedtschenkoi (Lavender scallops)

Plant non-specific lipid transfer protein (nsLTP) is able to bind and transport lipids and essential oils, as well as engage in various physiological processes, including defense against phytopathogens. Kalanchoe fedtschenkoi (Lavender Scallops) is an attractive and versatile succulent. To investigate the functional mechanism of Kalanchoe fedtschenkoi nsLTP (Ka-nsLTP), we expressed, purified and successfully obtained monomeric Ka-nsLTP. Mutational experiments revealed that the C6A variant retained the same activity as the wild-type (WT) Ka-nsLTP. Ka-nsLTP showed weak antiphytopathogenic bacterial activity, but inhibited fungal growth. Ka-nsLTP possessed a hydrophobic cavity effectively binding lauric acid. Our results offer novel molecular insights into the functional mechanism of nsLTP, which broadens our knowledge of the biological function of nsLTP in crops and provides a useful locus for genetic improvement of plants.

Polar-localized OsLTPG22 regulates rice leaf cuticle deposition and drought response

The cuticle serves as a crucial protective barrier for plant survival, and recent studies have highlighted the essential roles of nonspecific lipid transfer proteins (nsLTPs) in cuticle formation. However, the specific function of nsLTPs in the rice leaf cuticle remains unclear. In this study, we functionally characterized OsLTPG22, a G-type nsLTP with a signal peptide (SP) domain and a glycosylphosphatidylinositol (GPI) anchor region. Mutation in OsLTPG22 led to a reduction in cuticular wax abundance, increased leaf epidermal permeability, and higher drought sensitivity in seedlings. OsLTPG22 was widely expressed in various tissues and exhibited distinct polar localization to the aerial surface of epidermal cells in expanding leaves. OsLTPG22 binds lipids and localizes to the plasma membrane. Protein truncation experiments demonstrated that OsLTPG22’s polar localization was regulated by the SP domain, while both the SP domain and GPI anchor region regulated OsLTPG22’s plasma membrane localization. This work provides genetic and cytological evidence for OsLTPG22’s role in leaf cuticle formation and drought response, enhancing our understanding of nsLTP function and offering insights for breeding drought-resistant crops.

Application of CRISPR/Cas9 system to knock out GluB gene for developing low glutelin rice mutant

The nutritional quality improvement is among the most integral objective for any rice molecular breeding programs. The seed storage proteins (SSPs) have greater role to determine the nutritional quality of any cereal grains. Rice contains relatively balanced amino acid composition and the SSPs are fractioned into albumins (ALB), globulins (GLO), prolamins (PRO) and glutelins (GLU) according to differences in solubility. GLUs are further divided into subfamilies: GluA, GluB, GluC, and GluD depending on resemblance in amino acid. The GLU protein accounts for 60–80% of total protein contents, encoded by 15 genes located on different chromosomes of rice genome. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system was employed to knockout Glu-B (LOC-Os02g15070) gene in non-basmati rice PK386 cultivar. The mutant displayed two base pair and three base pair mutation in the targeted regions. The homozygous mutant plant displayed reduction for both in total protein contents and GLU contents whereas, elevation in GLO, ALB and PRO. Moreover, the mutant plant also displayed reduction in physio-chemical properties e.g., total starch, amylose and gel consistency. The agronomic characteristics of both mutant and wild type displayed non-significant differences along with increase in higher percentage of chalkiness in mutant plants. The results obtained from scanning electron microscopy showed the loosely packed starch granules compared to wild type. The gene expression analysis displayed the lower expression of gene at 5 days after flowering (DAF), 10 DAF, 15 DAF and 20 DAF compared to wild type. GUS sub-cellular localization showed the staining in seed which further validated the results obtained from gene expression. Based on these findings it can be concluded Glu-B gene have significant role in controlling GLU contents and can be utilized in breeding programs to enhance the nutritional quality of rice, and may serve as healthy diet for patient allergic with high GLU contents.

The Roadmap of Plant Antimicrobial Peptides Under Environmental Stress: From Farm to Bedside.

Antimicrobial peptides (AMPs) are the most favorable alternatives in overcoming multidrug resistance, alone or synergistically with conventional antibiotics. Plant-derived AMPs, as cysteine-rich peptides, widely compensate the pharmacokinetic drawbacks of peptide therapeutics. Compared to the putative genes encrypted in the genome, AMPs that are produced under stress are active forms with the ability to combat resistant microbial species. Within this study, plant-derived AMPs, namely, defensins, nodule-specific cysteine-rich peptides, snakins, lipid transfer proteins, hevein-like proteins, α-hairpinins, and aracins, expressed under biotic and abiotic stresses, are classified. We could observe that while α-hairpinins and snakins display a helix-turn-helix structure, conserved motif patterns such as β1αβ2β3 and β1β2β3 exist in plant defensins and hevein-like proteins, respectively. According to the co-expression data, several plant AMPs are expressed together to trigger synergistic effects with membrane disruption mechanisms such as toroidalpore, barrel-stave, and carpet models. The application of AMPs as an eco-friendly strategy in maintaining agricultural productivity through the development of transgenes and bio-pesticides is discussed. These AMPs can be consumed in packaging material, wound-dressing products, coating catheters, implants, and allergology. AMPs with cell-penetrating properties are verified for the clearance of intracellular pathogens. Finally, the dominant pharmacological activities of bioactive peptides derived from the gastrointestinal digestion of plant AMPs, namely, inhibitors of renin and angiotensin-converting enzymes, dipeptidyl peptidase IV and α-glucosidase inhibitors, antioxidants, anti-inflammatory, immunomodulating, and hypolipidemic peptides, are analyzed. Conclusively, as phytopathogens and human pathogens can be affected by plant-derived AMPs, they provide a bright perspective in agriculture, breeding, food, cosmetics, and pharmaceutical industries, translated as farm to bedside.

Complex of Defense Polypeptides of Wheatgrass (Elytrigia elongata) Associated with Plant Immunity to Biotic and Abiotic Stress Factors.

Plant defense polypeptides play a crucial role in providing plants with constitutive immunity against various biotic and abiotic stressors. In this study, we explored a complex of proteins from wheatgrass (Elytrigia elongata) spikelets to estimate their role in the plant's tolerance to various environmental factors. The current research shows that in vitro protein extracts from E. elongata spikelets possess antifungal activity against certain Fusarium species, which are specific cereal pathogens, at concentrations of 1-2 mg/mL. In this study, we reproduced these antifungal activities using a 4 mg/mL extract in artificial fungal infection experiments on wheat grain (Triticum aestivum) under controlled laboratory conditions. Furthermore, the tested extract demonstrated a protective effect on Saccharomyces cerevisiae exposed to hyper-salinity stress at a concentration of 2 mg/mL. A combined scheme of fractionation and structural identification was applied for the estimation of the diversity of defense polypeptides. Defensins, lipid-transfer proteins, hydrolase inhibitors (cereal bifunctional trypsin/alpha-amylase inhibitors from a Bowman-Birk trypsin inhibitor), and high-molecular-weight disease resistance proteins were isolated from the extract. Thus, wheatgrass spikelets appear to be a reservoir of defense polypeptides. Our findings contribute to a deeper understanding of plant defense proteins and peptides and their involvement in the adaptation to various stress factors, and they reveal the regulatory effect at the ecosystem level.

BnUC1 Is a Key Regulator of Epidermal Wax Biosynthesis and Lipid Transport in Brassica napus.

The bHLH (basic helix-loop-helix) transcription factor AtCFLAP2 regulates epidermal wax accumulation, but the underlying molecular mechanism remains unknown. We obtained BnUC1mut (BnaA05g18250D homologous to AtCFLAP2) from a Brassica napus mutant with up-curling leaves (Bnuc1) and epidermal wax deficiency via map-based cloning. BnUC1mut contains a point mutation (N200S) in the conserved dimerization domain. Overexpressing BnUC1mut in ZS11 (Zhongshuang11) significantly decreased the leaf epidermal wax content, resulting in up-curled and glossy leaves. In contrast, knocking out BnUC1mut in ZS11-NIL (Zhongshuang11-near-isogenic line) restored the normal leaf phenotype (i.e., flat) and significantly increased the leaf epidermal wax content. The point mutation weakens the ability of BnUC1mut to bind to the promoters of VLCFA (very-long-chain fatty acids) synthesis-related genes, including KCS (β-ketoacyl coenzyme synthase) and LACS (long-chain acyl CoA synthetase), as well as lipid transport-related genes, including LTP (non-specific lipid transfer protein). The resulting sharp decrease in the transcription of genes affecting VLCFA biosynthesis and lipid transport disrupts the normal accumulation of leaf epidermal wax. Thus, BnUC1 influences epidermal wax formation by regulating the expression of LTP and genes associated with VLCFA biosynthesis. Our findings provide a foundation for future investigations on the mechanism mediating plant epidermal wax accumulation.

Glycosylphosphatidylinositol-anchored lipid transfer proteins influence root cap cuticle formation at primary root tips, promoting NaCl tolerance in Arabidopsis seedlings.

Root cap cuticles (RCCs), comprising mainly very-long-chain fatty acids (VLCFAs), promote salt tolerance by preventing ion influx. Glycosylphosphatidylinositol-anchored lipid transfer protein (LTPG)1 and LTPG2 participate in VLCFA deposition in the extracellular region, aiding RCC formation in the lateral roots. In this study, we investigated whether LTPG1 and LTPG2 have similar functions in the primary roots of young Arabidopsis thaliana. Phenotypic analyses, fluorescence microscopy, and quantitative real-time reverse transcription polymerase chain reaction confirmed that NaCl exposure induced LTPG1 and LTPG2 expression and promoted RCC formation in young primary roots. The loss of RCC in the ltpg1 and ltpg2 mutants resulted in increased NaCl sensitivity of root elongation. NaCl also upregulated the expression of several NaCl-responsive genes in ltpg1 and ltpg2. We conclude that RCC formation via LTPG function is pivotal in enhancing salt tolerance in young primary roots.

Immunolocalization of hordein synthesis and transport in developing barley endosperm.

The spatial accumulation of hordeins in the developing endosperm of barley grains was examined by immunofluorescence microscopy (immunolight microscopy [iLM]) and immunoelectron microscopy (iEM) to establish the timing and subcellular pattern of hordein synthesis and deposition. The pattern seen for hordeins was compared to other abundant grain proteins, such as serpin Z4 and lipid transfer protein 1 (LTP1). Hordein accumulates throughout grain development, from 6 to 37 days post-anthesis (DPA). In contrast, serpin Z4 was present at 6 DPA, but the greatest synthesis and accumulation occurred during the middle of seed development, from 15 to 30 DPA. LTP1 accumulated later in seed development, from 15 to 30 DPA. Hordeins accumulated within the lumen of the endoplasmic reticulum (ER), were exocytosed from the ER membrane, and accumulated in protein bodies, which then fused either with the protein storage vacuoles or with other protein bodies, which also later fused with the protein storage vacuoles. iEM showed hordein, and LTP1 appeared not to traverse the Golgi apparatus (GA). Hordein, LTP1, and serpin Z4 colocalized to the same protein bodies and were co-transported to the protein storage vacuole in the same protein bodies. It is likely that this represents a general transport mechanism common to storage proteins in developing grains.

Long-chain fatty acids block allergic reaction against lipid transfer protein Sola l 7 from tomato seeds.

Due to the benefits of tomato as an antioxidant and vitamin source, allergy to this vegetable food is a clinically concerning problem. Sola l 7, a class I lipid transfer protein found in tomato seeds, has been identified as an allergen linked to severe anaphylaxis. However, the role of lipid binding in Sola l 7-induced allergy remains unclear. Here, the three-dimensional structure of recombinant Sola l 7 (rSola l 7) has been elucidated using nuclear magnetic resonance spectroscopy (NMR). Its interaction with free fatty acids has been deeply studied; fluorescence emission spectroscopy revealed that different long-chain fatty acids interact with the protein, affecting the only tyrosine residue present in Sola l 7. On the contrary, no changes in the overall secondary structure were observed after the analysis of the circular dichroism spectra in the presence of fatty acids. Unsaturated oleic and linoleic fatty acids presented higher affinity and promoted more significant changes than saturated or short-chain fatty acids. 1H-15N HSQC NMR spectra allowed to determine the regions of the protein that were modified when rSola l 7 interacts with the fatty acids, suggesting epitope modification after the interaction. For corroboration, IgG and IgE binding to rSola l 7 were assessed in the presence of free fatty acids, revealing that both IgE and IgG binding were significantly lower than in their absence, suggesting a potential protective role of unsaturated fatty acids in tomato allergy.