Expression and characterization of Rv2430c, a novel immunodominant antigen of Mycobacterium tuberculosis

Choudhary, Rakesh K. ; Pullakhandam, Raghu ; Ehtesham, Nasreen Z. ; Hasnain, Seyed E. (2004) Expression and characterization of Rv2430c, a novel immunodominant antigen of Mycobacterium tuberculosis Protein Expression and Purification, 36 (2). pp. 249-253. ISSN 1046-5928

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S10465...

Related URL: http://dx.doi.org/10.1016/j.pep.2004.03.016

Abstract

About 10% of the coding sequence of Mycobacterium tuberculosis corresponds to hitherto unknown members of the PE and PPE protein families which display significant sequence and length variation at their C-terminal region. It has been suggested that this could possibly represent a rich source of antigenic variation within the pathogen. We describe the purification and biophysical characterization of the recombinant PPE protein coded by hypothetical ORF Rv2430c, a member of the PPE gene family that was earlier shown to induce a strong B cell response. Expression of the recombinant PPE protein in Escherichia coli led to its localization in inclusion bodies and subsequent refolding using dialysis after its extraction from the same resulted in extensive precipitation. Therefore, an on-column refolding strategy was used, after which the protein was found to be in the soluble form. CD spectrum of the recombinant protein displayed predominantly α helical content (81%) which matched significantly with in silico and web-based secondary structure predictions. Furthermore, fluorescence emission spectra revealed that aromatic amino acids are buried inside the protein, which are exposed to aqueous environment under 8 M urea. These results, for the first time, provide evidence on the structural features of PPE family protein which, viewed with its reported immunodominant characteristics, have implications for other proteins of the PE/PPE family.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Rv2430c; Mycobacterium tuberculosis; On Column Refolding
ID Code:15591
Deposited On:13 Nov 2010 12:52
Last Modified:03 Jun 2011 06:33

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