Alpha S1-casein polymorphisms in camel (Camelus dromedarius) and descriptions of biological active peptides and allergenic epitopes

Abstract

Milk samples of 193 camels (Camelus dromedarius) from different regions of Sudan were screened for casein variability by isoelectric focusing. Kappa-casein and beta-casein were monomorphic, whereas three protein patterns named αs1-casein A, C, and D were identified. The major allele A revealed frequencies of 0.79 (Lahaoi), 0.75 (Shanbali), 0.90 (Arabi Khali), and 0.88 (Arabi Gharbawi) in the different ecotypes. CSN1S1*C shows a single G > T nucleotide substitution in the exon 5, leading to a non-synonymous amino acid exchange (p.Glu30 > Asp30) in comparison to CSN1S1*A and D. At cDNA level, no further single nucleotide polymorphisms could be identified in CSN1S1* A, C, and D, whereas the variants CSN1S1*A and CSN1S1*C are characterized by missing of exon 18 compared to the already described CSN1S1*B, as consequence of DNA insertion of 11 bp at intron 17 which alter the pre-mRNA spliceosome machinery. A polymerase chain-restriction fragment length polymorphism method (PCR-RFLP) was established to type for G > T nucleotide substitution at genomic DNA level. The occurrence and differences of IgE-binding epitopes and bioactive peptides between αs1-casein A, C, and D after digestion were analyzed in silico. The amino acid substitutions and deletion affected the arising peptide pattern and thus modifications between IgE-binding epitopes and bioactive peptides of the variants were found. The allergenic potential of these different peptides will be investigated by microarray immunoassay using sera from milk-sensitized individuals, as it was already demonstrated for bovine αs1-casein variants.

Old World camels in a modern world – a balancing act between conservation and genetic improvement

“…As in cow milk ca. 80% of the total protein fraction of camel milk is represented by caseins (CN), consisting of a s1 -, a s2 -, b-, c-, and j-CN (Erhardt et al 2016;Ryskaliyeva et al 2018;Singh et al 2018), as well as a b-CN short isoform (Ryskaliyeva et al 2018). Whereas band j-CN were monomorphic, three different genetic variants (A, C and D) were identified in the a s1 -CNs (Erhardt et al 2016).…”

“…80% of the total protein fraction of camel milk is represented by caseins (CN), consisting of a s1 -, a s2 -, b-, c-, and j-CN (Erhardt et al 2016;Ryskaliyeva et al 2018;Singh et al 2018), as well as a b-CN short isoform (Ryskaliyeva et al 2018). Whereas band j-CN were monomorphic, three different genetic variants (A, C and D) were identified in the a s1 -CNs (Erhardt et al 2016). Overall, milk whey proteins were reported to display a wide range of bioactivities including immune modulating, antibacterial and antifungal activities (reviewed in Mati et al 2017).…”

Molecular characterization and genetic variability of Alpha Casein gene, CSN1S1 in Bikaneri camel (Camelus dromedarius) milk

“…Camel -casein may exist as several variants. Erhardt (2016) and workers have worked on casein gene polymorphism in milk samples of camels from different regions of Sudan (Africa) by isoelectric focusing, where three protein patterns named -casein A, C, and D were identified. The major allele A revealed frequencies of 0.79 (Lahaoi), 0.75 (Shanbali), 0.90 (Arabi Khali), and 0.88 (Arabi Gharbawi) in the different ecotypes.…”

Databases and Associated Bioinformatic Tools in Studies of Food Allergens, Epitopes and Haptens – a Review

“…The database also enables performing calculations, such as epitope profi les, i.e., determining the location of epitopes in a protein sequence, known as in silico epitope mapping [Leung et al, 2014]. The database may be suitable for the determination of epitope profi les for potential allergens belonging to families grouping proteins with amino acid sequences containing many common fragments such as caseins [Erhardt et al, 2016], tropomyosins [Marti et al, 2007] or prolamins [Minkiewicz et al, 2015]. For protein families with highly variable sequences such as fi sh parvalbumins [Carrera et al, 2006], the analysis of common epitopes in silico using the BIOPEP database may provide no results.…”