In silico Annotation and Antigenic Peptide Identification of Staphylococcus Enterotoxins

Author Name(s): D.Gayathri, M.Shiva Prakash
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Staphylococcus has long back gained its importance in causing several diseases especially skin diseases. It is known to have the capability of enterotoxin production which constitutes for its pathogenicity. Being resistant to several antibiotics, causes hurdles in the treatment. The current work aimed to annotate in detail the selected Enterotoxins SEA, SEB, SEC, SED and SEE. The annotation includes the collection of gene sequences from NCBI Data base, Translating and obtaining the protein product of the sequences. Identification of functional domains in the protein sequence, structure prediction, Antigenic site identification and propensity calculations were performed. The 3D Structure of the protein was observed in Rasmol Software. The Foreignness of the sample to the human proteome was identified using TFAST Y of SDSC Biology workbench. The overall work emphasis on the analysis of enterotoxin pathogenicity of Staphylococcus aureus.


Enterotoxin, Antigenicity, Foreignness, TFASTY


Staphylococcus aureus  is gram positive cocci found in clusters. It is long being known for its pathogenicity against humans by causing several skin related aberrations. This group of bacteria are known to produce enterotoxins which are the actual cause for their pathogenicity. These are facultative anaerobic species, showing a positive test for Catalase and nitrate reduction. The enterotoxins produced by staphylococcus include SEA, SEB, SEC, SED and SEE. All the toxins are known to cause human skin infections. The use of antibiotics to treat staphylococcal infections would face a severe challenge due to the antibiotic resistance shown by these strains. Methicillin resistant staphylococcus is well known for its toughness towards several antibiotics used for its treatment. The enterotoxins produced by these bacteria are proteinacious in nature and have potential pathogenicity to provoke the immune components of the host thereby causing infections. Staphylococcal human skin infections especially by Community associated Methicillin resistant staphylococcus aureus (CA-MRSA) have been a global health problem within a short span of time.

Use of Bioinformatics in the analysis of biological data especially the medical data has been the current era research. Several insilico tools and softwares enable the complete annotation of the gene and its translated protein product. In the current work the physiological, Biochemical, functional and structural parameters of the 5 Enterotoxins A, B, C, D and E have been considered.  Several tools like Protparam, TFASTY, EMBOSS, phyre etc have been used to perform the annotation. The study focusses on identifying the exact antigenic regions on these enterotoxin units so as to develop a structural analogue or a vaccine against the same to prevent the infections.


As per the above analysis one important conclusion though known theoretically is that the pathogenicity and foreignness of all the five peptides to the human proteome. Higher the degree of foreignness greater is the chances of causing diseases. It can also be concluded that out of all the 5 Peptides SEA has maximum number of pathogenic sites which imparts for its high pathogenicity. The work also emphasized on the identification of pathogenic sites called paratopic regions on the proteins that can bind to and recognized by the epitomic sites of antibodies. Structural analysis of the peptides proved that SEA, SEB and SED show greater structural similarity when compared to the SEC and SEE.

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