For making this plasmid, we first P5091 amplified the DNA fragment containing the coding region of Obg of M. tuberculosis by PCR, using the primers TBOBG5 and TBOBG6. The amplified DNA fragment was cut with BamHI and cloned into the BamHI site of pMV261 [46] downstream of the hsp60 promoter. Plasmid pGB2440c, for Obg expression in yeast, was created by cloning the NdeI-BamHI fragment

containing obg from pOBGE into NdeI-BamHI-cut pGBKT7. Finally, plasmid pGA2853c, for RelA expression in yeast, was created by cloning the NdeI and BamHI cut DNA fragment containing the relA gene (Rv2853) amplified using primers TBRELAF and TBRELAR, into pGADT7. The cloned DNA fragments in all plasmids were verified by DNA sequencing for their appropriateness. All plasmids that we used in this study are described in Table 3. Table 3 List of plasmids used in this study. Plasmid Description Reference/source pCR2.1 oriColE1, lacZα, Plac, aph, AmpR Invitrogen pMV261 oriE, oriM, Phsp60, aph Stover see more et al, SAR302503 nmr 1991 pMVOBG pMV261-Rv2440c full orf This study pET16b oriE, lacI, PT7, AmpR Novagen pTBOBGE pET16B-Rv2440c full orf This study pGADT7 oriColE1, ori2 μ, LEU1, PADH1::GAL4′ activator domain::MCS AmpR Clontech pGBKT7 oriColE1, ori2 μ, TRP1, PADH1::GAL4′ binding domain::MCS

KmR Clontech pGADT7-T SV40 large T-antigen(84-708) in pGADT7 Clontech pGBKT7-53 Murine p53(72-390) in pGBKT7 Clontech pGBKT7-Lam Human lamin C(66-230) in pGBKT7 Clontech pGA2853c pGADT7-Rv2853c full orf This study pGB3286c pGBKT7-Rv3286c full orf Parida et al, 2005 pGA3287c pGADT7-Rv3287c full orf Parida et al, 2005 pGB2440c pGBKT7-Rv2440c full orf This study Overexpression of M. tuberculosis Obg in E. coli and production of antiserum The E. coli-overexpressed Obg protein of M. tuberculosis was purified in its native condition.

The plasmid construct pTBOBGE was transformed into E. coli strain BL21(DE3). A single transformant colony was selected and grown in 2 ml of LB broth overnight. One ml of this overnight culture was inoculated into 250 ml LB broth and grown to log phase (0.350 OD at 590 nm) at 37°C. IPTG (1 mM) was then added to the culture to induce overexpression of Obg, and the culture was grown Monoiodotyrosine for an additional 3 h. Afterwards, E. coli cells were harvested by centrifugation (5,000 g for 10 min at 4°C) and stored overnight at -80°C. The pellet was resuspended in 5 ml of lysis buffer (50 mM NaH2PO4 pH 8.0, 300 mM NaCl, 10 mM Imidazole) containing 1 mg/ml of lysozyme, incubated on ice for 30 min and the cells disrupted by sonication. The lysate was centrifuged at 12,000 g, and the supernatant was loaded on to a 2 ml Ni-NTA column (Qiagen). After washing the column with 50 ml of wash buffer (50 mM NaH2PO4 pH 8.0, 300 mM NaCl, 20 mM Imidazole), the column- bound Obg protein (His10-Obg) was eluted with 2 ml of elution buffer (50 mM NaH2PO4 pH 8.0, 300 mM NaCl, 250 mM Imidazole). The eluted fraction was dialyzed against 2 L of 20 mM Tris-HCl pH 8.0 containing 5% glycerol.