Expression, immunochemical characterization and localization of the Mycobacterium tuberculosis protein p27

P27-PPE36 (Rv2108) Mycobacterium tuberculosis Antigen – Member of PPE Protein Family with Surface Localization and Immunological Activities

“…Similar results were obtained using western-blot analysis (Fig. 4 D) of the Mtb cell fractions with the monoclonal anti-P27-PPE36 antibody indicating that the P27-PPE36 protein is localized in the membrane of the cell (Le Moigne et al, 2005). This protein was the third member of its family to be localized at the periphery of the cell Pym et al, 2002;Okkels et al, 2003;Demangel et al, 2004) and since, the same localization was assigned to other PPE proteins like for exemple Map3420c and Map1506 in Mycobacterium avium subsp.…”

“…Our attemps to express P27-PPE36 under the form of a recombinant proteins confirm this rules and lead to the obtention of an insoluble protein (Le Moigne et al, 2005), as confirmed later by an other study (Strong et al, 2006). The lack of apparent transmembrane elements is a possible explanation for their failure to express on their own is that they need protein partners to fold (Strong et al, 2006) like explained above in the Genomic organization paragraph.…”

“…This value was higher than the theoretical mass predicted by its DNA sequence translation of 27 kDa. Mass spectrometric analysis of the expressed protein in the pET system revealed a molecule at 29 kDa, which corresponds to the P27-PPE36 putative protein estimated mass plus 2 kDa for the polyHistidine fusion Tag (Le Moigne et al, 2005). This result was confirmed by partial sequencing of the N-terminal region of the recombinant protein.…”

“…Specific immunoblot analysis confirmed the presence of the P27-PPE36 antigen in Mycobacterium bovis BCG strain and in human clinical isolates of M. tuberculosis from infected patients (Fig. 3), but not in other mycobacteria tested which does not belong to the Mtb complex (Le Moigne et al, 2005).…”

“…A putative interaction PE22/PPE36 is probably under the form of a 1:1 heterodimeric complex (Strong et al, 2003). In their study, they found, as us (Le Moigne et al, 2005), that PPE36 is insoluble when expressed alone. The association with the relative PE protein would lead to a soluble complex: their experiments showed that proteins PE Rv2431c and PPE Rv2430 that are insosuble when expressed on their own are soluble when they are expressed together (Strong et al, 2006;Tundup et al, 2006).…”