Dataset Information

Biotin-Labelled Clavulanic Acid to Identify Proteins Target for Haptenation in Serum

ABSTRACT: Clavulanic acid (CLV) is a betalactam (BL) which inhibits betalactamases activity and is frequently administered combined with amoxicillin (AX). Both BLs can be independently involved in allergic reactions. Indeed, selective immediate allergic reactions to CLV have recently been reported in 30% of patients allergic to the AX-CLV combination. Although protein haptenation with β-lactams is considered necessary to activate the immune system, currently there are no straight-forward detection tools for the study of protein haptenation by CLV. The aim of this study was to assess the suitability of two biotinylated analogues of CLV, CLV-B or CLV-TEG-B (containing the later a hydrophilic tetraethylenglycol linker), as probes to study protein haptenation by this β-lactam. Our results show that tagged CLV keeps some of the features of CLV, as the amide binding by which they haptenate proteins and it could constitute a valuable tool to identify protein targets for haptenation by CLV with high sensitivity to get insights into the activation of the immune system by CLV as well as mechanisms involved in allergy to β-lactams.

INSTRUMENT(S): 4800 Plus MALDI TOF/TOF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Blood Serum

SUBMITTER: Concha Gil

LAB HEAD: María Isabel Montañez Vega

PROVIDER: PXD021675 | Pride | 2021-09-09

REPOSITORIES: Pride

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Biotin-Labelled Clavulanic Acid to Identify Proteins Target for Haptenation in Serum: Implications in Allergy Studies.

Martín-Serrano Ángela Á Gonzalez-Morena Juan M JM Barbero Nekane N Ariza Adriana A Sánchez Gómez Francisco J FJ Pérez-Inestrosa Ezequiel E Pérez-Sala Dolores D Torres Maria J MJ Montañez María I MI

Frontiers in pharmacology 20201118

Clavulanic acid (CLV) and amoxicillin, frequently administered in combination, can be independently involved in allergic reactions. Protein haptenation with β-lactams is considered necessary to activate the immune system. The aim of this study was to assess the suitability of biotinylated analogues of CLV as probes to study protein haptenation by this β-lactam. Two synthetic approaches afforded the labeling of CLV through esterification of its carboxylic group with a biotin moiety, via either di ...[more]

PMID: 33442385

Similar Datasets

Project description:Clavulanic acid (CLV) and amoxicillin, frequently administered in combination, can be independently involved in allergic reactions. Protein haptenation with β-lactams is considered necessary to activate the immune system. The aim of this study was to assess the suitability of biotinylated analogues of CLV as probes to study protein haptenation by this β-lactam. Two synthetic approaches afforded the labelling of CLV through esterification of its carboxylic group with a biotin moiety, via either direct binding (CLV-B) or tetraethylenglycol linker (CLV-TEG-B). The second analogue offered advantages as solubility in aqueous solution and potential lower steric hindrance for both intended interactions, with the protein and with avidin. NMR reactivity studies showed that both CLV and CLV-TEG-B reacts through β-lactam ring opening by aliphatic amino nitrogen, however with different stability of resulting conjugates. Unlike CLV conjugates, that promoted the decomposition of clavulanate fragment, the conjugates obtained with the CLV-TEG-B remained linked, as a whole structure including biotin, to nucleophile and showed a better stability. This was a desired key feature to allow CLV-TEG-B conjugated protein detection at great sensitivity. We have used biotin detection and mass spectrometry (MS) to detect the haptenation of human serum albumin (HSA) and human serum proteins. MS of conjugates showed that HSA could be modified by CLV-TEG-B. Remarkably, HSA preincubation with CLV excess only reduced moderately the incorporation of CLV-TEG-B, which could be attributed to different protein interferences. The CLV-TEG-B fragment with opened β-lactam was detected bound to the 404-430HSA peptide of the treated protein. Incubation of human serum with CLV-TEG-B resulted in the haptenation of several proteins that were identified by 2D-electrophoresis and peptide mass fingerprinting as HSA, haptoglobin, and heavy and light chains of immunoglobulins. Taken together, our results show that tagged-CLV keeps some of the CLV features. Moreover, although we observe a different behaviour in the conjugate stability and in the site of protein modification, the similar reactivity indicates that it could constitute a valuable tool to identify protein targets for haptenation by CLV with high sensitivity to get insights into the activation of the immune system by CLV and mechanisms involved in β-lactams allergy.

Project description:Nearly 50% of cutaneous melanomas carry activating mutations on the BRAF oncogene, and the combination of BRAF- and MEK-inhibitors (BRAF/MEKi) is frequently used for their clinical management. One major drawback of BRAF/MEKi targeted therapy is the rapid development of therapeutic resistance, which can occur via multiple mechanisms, including the metabolic rewiring of cancer cells that often involves the upregulation of mitochondrial bionergetics and NAD+ biosynthetic pathways. mTORC2 is a signaling complex that requires the presence of its essential RICTOR subunit to play its regulatory functions in cell growth and metabolism. mTORC2 is believed to play mostly pro-oncogenic roles in several tumor types, including melanoma. However, bioinformatics analysis of TCGA melanoma patients’ database revealed that low RICTOR levels in tumors correlate with an overall worse clinical outcome. GSEA analysis of low-RICTOR tumors evidenced also a gene expression signature suggestive of activation of mitochondrial energy producing pathways. On these bases, we have hypothesized that inhibition of mTORC2 activity may render BRAFV600E melanoma cells resistant to BRAFi/MEKi. We show here that RICTOR/mTORC2-deficient cells are intrinsically tolerant to BRAFi/MEKi, and anticipate the onset of resistance to BRAFi after sustained drug exposure both in vitro and in vivo, indicating that mTORC2 activity normally opposes the acquisition of targeted therapy resistance in BRAFV600E melanomas. Mechanistically, RICTOR-deficient cells show an enhanced mitochondrial respiratory potential and increased expression of nicotinamide phosphoribosyltransferase (NAMPT) protein, the rate-limiting enzyme of NAD+ salvage pathway, and pharmacological inhibition of these processes in RICTOR-deficient cells is sufficient to restore sensitivity to BRAFi. Thus, our work identifies a novel role for mTORC2 in favoring the responses of BRAF-mutated melanoma cells to targeted therapy, and suggest that the evaluation of the intratumor level of RICTOR may help to predict the responses of melanoma patients to these treatments.

Project description:Purpose: Delonix regia or Gulmohor commonly grows here and there in Indian villages as well as it is used for megacity beautification and environmental management due to its evergreen nature and vibrant flower colour. However, an increasing incidence of seasonal pollinosis was observed among the inhabitants living in close vicinity to this tree suggesting a possible link between the airborne pollen load and the concomitant respiratory hazards. This prompted us to investigate the allergens in the pollen of this dominant avenue tree. Methodology: Allergenicity of D. regia pollen grains was first checked by Skin Prick Test (SPT) and further confirmed by in vitro tests, such as, ELISA, Dot Blot and histamine release assay. The total proteome profiling was done by 2D PAGE and it was confronted with the pooled sera of 10 patients. The IgE reactive proteins were identified by MALDI TOF/TOF in Autoflex speed (Bruker,Germany). The raw spectra were searched against NCBInr database using MASCOT search engine. Result: Delonix regia, pollen grains have been found in considerable amount in the air during its flowering season (May to July). Approximately 31% of atopic individuals were found allergic to D. regia, pollen with elevated level of specific IgE and histamine in the serum. Total 8 IgE reactive proteins have been identified by homology driven proteomics. These proteins are ATP synthase beta subunit (spot no 5), Actin (spot no 6), Hypothetical actin like protein (spot no 7), Recombinant S-adenosylmethionine synthase 2 (spot no 9), UDP-arabinopyranose mutase (spot no 13), Luminal-binding 5 (spot no 2), ELF3-like protein (spot no 8) and hypothetical protein OsJ_04810 (spot no 11). Among these eight identified allergenic proteins, five were previously reported as allergen from different sources whereas the rest three have been reported for the first time as novel allergens. Conclusion: Novelty of this study was to identify 8 allergens from D.regia for the first time using immune-biochemical and proteomic techniques. Further studies will open up new avenues in component resolved diagnosis of pollen allergy.

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	F003723.dat	Other
	F003723.mgf	Mgf
	F003724.dat	Other
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	F003725.dat	Other