title: Truncation of PstS1 antigen of Mycobacterium tuberculosis improves diagnostic efficiency.
abstract: PstS1, also named 38-kDa antigen, is one of the earliest known immune-dominant antigens of Mycobacterium tuberculosis and it has been commonly used in serodiagnostic tests. We constructed a truncated version, tnPstS1, by removing 96 and 14 amino acid residues from the N- and C-terminals, respectively of the native PstS1. The native and the truncated 29.5 kDa proteins were expressed in insoluble forms in Escherichia coli to levels of 15% and 25% of the total cell proteins, respectively. Both the variant molecules reacted equally well with the antisera raised in rabbit against the native protein. PstS1 and tnPstS1 were evaluated through ELISA against plasma samples from 160 culture positive tuberculosis patients and 40 healthy controls. With tnPstS1 43% of the patient samples were detected positive for the antibody as compared to only 36% in the case of the native PstS1. Data for the secondary structures of the native and the truncated variants as obtained by circular dichroism agreed with the known 3-D structure of the native protein and the predicted structure of the truncated version, respectively. The results show that the truncated tnPstS1 is more efficient as compared to the native PstS1 for use as a serodiagnostic agent.
authors: School of Biological Sciences, Quaid-e-Azam Campus, University of the Punjab, Lahore 54590, Pakistan.
authors: Sana
authors: S
authors: Khurshid
authors: Ruqyya
authors: R
authors: Khalid
authors: Madeeha
authors: M
authors: Afzal
authors: M
authors: M
authors: Waheed Akhtar
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology*; D016022:Case-Control Studies; D002942:Circular Dichroism / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D058849:Protein Refolding; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology; D014376:Tuberculosis / Q000175:diagnosis*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C102010:PstS-3 protein, Mycobacterium tuberculosis; D011994:Recombinant Proteins; C072681:Mycobacterium tuberculosis antigens
keywords: Mycobacterium tuberculosis; PstS1; Tuberculosis; tnPstS1